The World Health Organization (WHO) lists ego-dystonic sexual orientation in the ICD-10, as a disorder of sexual development and orientation. The WHO diagnosis covers when gender identity or sexual orientation is clear, yet a patient has another behavioural or psychological disorder which makes that patient want to change it. The diagnostic manual notes that a sexual orientation is not a disorder in itself. The World Health Organization (WHO) notes that any particular sexual orientation (heterosexuality, homosexuality, or bisexuality) is not a mental disorder by and of itself.

Similarly, the American Psychological Association has officially opposed the category of ego-dystonic homosexuality since 1987. In 2007, a task force of the American Psychological Association undertook a thorough review of the existing research on the efficacy of reparative therapy for. Their report noted that there was very little methodologically sound research on sexual orientation change efforts (SOCEs) and that the "results of scientifically valid research indicate that it is unlikely that individuals will be able to reduce same-sex attractions or increase other-sex sexual attractions through SOCE." In addition, the task force found that "there are no methodologically sound studies of recent SOCE that would enable the task force to make a definitive statement about whether or not recent SOCE is safe or harmful and for whom." The diagnostic category of "ego-dystonic homosexuality" was removed from the American Psychiatric Association's DSM in 1987 (with the publication of the DSM-III-R). Sexual disorders are still present in the DSM under the category of "sexual disorder not otherwise specified". One of the disorders under this category is "persistent and marked distress about one’s sexual orientation”, which can be considered similar to what WHO describes as ego-dystonic sexual orientation.

The Medical Council of India uses the WHO classification of ego-dystonic sexual orientation. The "Chinese Classification and Diagnostic Criteria of Mental Disorders" includes ego-dystonic homosexuality.

Ego-dystonic sexual orientation is an ego-dystonic mental disorder characterized by having a sexual orientation or an attraction that is at odds with one's idealized self-image, causing anxiety and a desire to change one's orientation or become more comfortable with one's sexual orientation. It describes not innate sexual orientation itself, but a conflict between the sexual orientation one wishes to have and the sexual orientation one actually possesses.

Paraphilia (previously known as sexual perversion and sexual deviation) is the experience of intense sexual arousal to atypical objects, situations, fantasies, behaviors, or individuals. Such attraction may be labeled sexual fetishism. No consensus has been found for any precise border between unusual sexual interests and paraphilic ones. There is debate over which, if any, of the paraphilias should be listed in diagnostic manuals, such as the "Diagnostic and Statistical Manual of Mental Disorders" (DSM) or the International Classification of Diseases (ICD).

The number and taxonomy of paraphilia is under debate; one source lists as many as 549 types of paraphilia. The DSM-5 has specific listings for eight paraphilic disorders. Several sub-classifications of the paraphilias have been proposed, and some argue that a fully dimensional, spectrum or complaint-oriented approach would better reflect the evidence.

Transvestism is the practice of dressing and acting in a style or manner traditionally associated with the opposite sex. In some cultures, transvestism is practiced for religious, traditional or ceremonial reasons.

Biphobia is aversion toward bisexuality and toward bisexual people as a social group or as individuals. It can take the form of denial that bisexuality is a genuine sexual orientation, or of negative stereotypes about people who are bisexual (such as the beliefs that they are promiscuous or dishonest). People of any sexual orientation can experience or perpetuate biphobia, and it is a source of social discrimination against bisexual people.

The following are some of the partialisms commonly found among people:

As a paraphilia, breast fetishism (also known as mastofact, breast partialism, or mazophilia) is a highly atypical sexual interest focused on female breasts (see partialism). The term "breast fetishism" is also used in the non-paraphilic sense, to refer to cultural attention to female breasts and the sexuality they represent, with debate existing as to whether the modern widespread fascination with breasts among heterosexual males in western societies is a sexual fetish.

Males with late onset gender dysphoria "frequently" display transvestic fetishism.

Some male transvestic fetishists collect women's clothing, e.g. panties, nightgowns, babydolls, bridal gowns, slips, brassieres, and other types of nightwear, lingerie, stockings, pantyhose, shoes, and boots, items of a distinct feminine look and feel. They may dress in these feminine garments and take photographs of themselves while living out their fantasies.

According to DSM-IV, this fetishism was limited to heterosexual men; however, DSM-5 does not have this restriction, and opens it to women and men with this interest, regardless of their sexual orientation.

There are two key criteria before a psychiatric diagnosis of "transvestic fetishism" is made:

1. Individuals must be sexually aroused by the act of cross-dressing.

2. Individuals must experience significant distress or impairment – socially or occupationally – because of their behavior.

The DSM-5 adds a distinction between "paraphilias" and "paraphilic disorders", stating that paraphilias do not require or justify psychiatric treatment in themselves, and defining "paraphilic disorder" as "a paraphilia that is currently causing distress or impairment to the individual or a paraphilia whose satisfaction has entailed personal harm, or risk of harm, to others".

The DSM-5 Paraphilias Subworkgroup reached a "consensus that paraphilias are not "ipso facto" psychiatric disorders", and proposed "that the DSM-V make a distinction between "paraphilias" and paraphilic "disorders". [...] One would "ascertain" a paraphilia (according to the nature of the urges, fantasies, or behaviors) but "diagnose" a paraphilic disorder (on the basis of distress and impairment). In this conception, having a paraphilia would be a necessary but not a sufficient condition for having a paraphilic disorder." The 'Rationale' page of any paraphilia in the electronic DSM-5 draft continues: "This approach leaves intact the distinction between normative and non-normative sexual behavior, which could be important to researchers, but without automatically labeling non-normative sexual behavior as psychopathological. It also eliminates certain logical absurdities in the DSM-IV-TR. In that version, for example, a man cannot be classified as a transvestite—however much he cross-dresses and however sexually exciting that is to him—unless he is unhappy about this activity or impaired by it. This change in viewpoint would be reflected in the diagnostic criteria sets by the addition of the word "Disorder" to all the paraphilias. Thus, Sexual Sadism would become Sexual Sadism Disorder; Sexual Masochism would become Sexual Masochism Disorder, and so on."

Bioethics professor Alice Dreger interpreted these changes as "a subtle way of saying sexual kinks are basically okay – so okay, the sub-work group doesn’t actually bother to define paraphilia. But a paraphilic disorder is defined: that’s when an atypical sexual interest causes distress or impairment to the individual or harm to others." Interviewed by Dreger, Ray Blanchard, the Chair of the Paraphilias Sub-Work Group, explained: "We tried to go as far as we could in depathologizing mild and harmless paraphilias, while recognizing that severe paraphilias that distress or impair people or cause them to do harm to others are validly regarded as disorders."

Charles Allen Moser pointed out that this change is not really substantive as DSM-IV already acknowledged a difference between paraphilias and non-pathological but unusual sexual interests, a distinction that is virtually identical to what is being proposed for DSM-5, and it is a distinction that, in practice, has often been ignored. Linguist Andrew Clinton Hinderliter argued that "Including some sexual interests—but not others—in the DSM creates a fundamental asymmetry and communicates a negative value judgment against the sexual interests included," and leaves the paraphilias in a situation similar to ego-dystonic homosexuality, which was removed from the DSM because it was realized not to be a mental disorder.

The DSM-5 acknowledges that many dozens of paraphilias exist, but only has specific listings for eight that are forensically important and relatively common. These are voyeuristic disorder, exhibitionistic disorder, frotteuristic disorder, sexual masochism disorder, sexual sadism disorder, pedophilic disorder, fetishistic disorder, and transvestic disorder. Other paraphilias can be diagnosed under the Other Specified Paraphilic Disorder or Unspecified Paraphilic Disorder listings, if accompanied by distress or impairment.

BDSM is a variety of often erotic practices or roleplaying involving bondage, discipline, dominance and submission, sadomasochism, and other related interpersonal dynamics. Given the wide range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent upon self-identification and shared experience.

The term "BDSM" is first recorded in a Usenet posting from 1991, and is interpreted as a combination of the abbreviations B/D (Bondage and Discipline), D/s (Dominance and submission), and S/M (Sadism and Masochism). BDSM is now used as a catch-all phrase covering a wide range of activities, forms of interpersonal relationships, and distinct subcultures. BDSM communities generally welcome anyone with a non-normative streak who identifies with the community; this may include cross-dressers, body modification enthusiasts, animal roleplayers, rubber fetishists, and others.

Activities and relationships within a BDSM context are often characterized by the participants taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners is essential. The terms "submissive" and "dominant" are often used to distinguish these roles: the dominant partner ("dom") takes psychological control over the submissive ("sub"). The terms "top" and "bottom" are also used: the top is the instigator of an action while the bottom is the receiver of the action. The two sets of terms are subtly different: for example, someone may choose to act as bottom to another person, for example, by being whipped, purely recreationally, without any implication of being psychologically dominated by them, or a submissive may be ordered to massage their dominant partner. Despite the bottom performing the action and the top receiving they have not necessarily switched roles.

The abbreviations "sub" and "dom" are frequently used instead of "submissive" and "dominant". Sometimes the female-specific terms "mistress", "domme" or "dominatrix" are used to describe a dominant woman, instead of the gender-neutral term "dom". Individuals who can change between top/dominant and bottom/submissive roles—whether from relationship to relationship or within a given relationship—are known as "switches". The precise definition of roles and self-identification is a common subject of debate within the community.

Transmisogyny (sometimes trans-misogyny) is the intersection of transphobia and misogyny. Transphobia is defined as "the irrational fear of, aversion to, or discrimination against transgender or transsexual people". Misogyny is defined as "a hatred of women". Therefore, transmisogyny includes negative attitudes, hate, and discrimination of transgender or transsexual individuals who fall on the feminine side of the gender spectrum, particularly transgender women. The term was coined by Julia Serano in her 2007 book "Whipping Girl" and used to describe the unique discrimination faced by trans women because of "the assumption that femaleness and femininity are inferior to, and exist primarily for the benefit of, maleness and masculinity", and the way that transphobia intensifies the misogyny faced by trans women (and vice versa). It is said many trans women experience an additional layer of misogyny in the form of fetishization; Serano talks about how society views trans women in certain ways that sexualize them, such as them transitioning for sexual reasons, or ways where they’re seen as sexually promiscuous.Transmisogyny is a central concept in transfeminism and is commonly referenced in intersectional feminist theory. That trans women's femaleness (rather than only their femininity) is a source of transmisogyny is denied by certain radical feminists, who claim that trans women are not female.

Lesbophobia (sometimes lesbiphobia) comprises various forms of negativity towards lesbians as individuals, as couples, or as a social group. Based on the categories of sex, sexual orientation, lesbian identity, and gender expression, this negativity encompasses prejudice, discrimination, and abuse, in addition to attitudes and feelings ranging from disdain to hostility. As such, lesbophobia is sexism against women that intersects with homophobia and vice versa.

Partialism is sexual interest with an exclusive focus on a specific part of the body other than the genitals. Partialism is categorized as a fetishistic disorder in the DSM-5 of the American Psychiatric Association only if it causes significant psychosocial distress for the person or has detrimental effects on important areas of their life. In the DSM-IV, it was considered a separate paraphilia (not otherwise specified), but was merged into fetishistic disorder by the DSM-5. Individuals who exhibit partialism sometimes describe the anatomy of interest to them as having equal or greater erotic attraction for them as do the genitals.

Partialism occurs in heterosexual, bisexual, and homosexual individuals. The foot is considered one of the most common partialisms.

Children with persistent GID are characterized by more extreme gender dysphoria in childhood than children with desisting gender dysphoria. Some (but not all) gender diverse / gender independent / gender fluid youth will want or need to transition, which may involve social transition (changing dress, name, pronoun), and, for older youth and adolescents, medical transition (hormonal and surgical intervention). Treatment may take the form of puberty blockers such as Lupron Depot or Leuprolide Acetate, or cross-sex hormones (i.e., administering estrogen to an assigned male at birth or testosterone to an assigned female at birth), or surgery (i.e., mastectomies, salphingo-oophorectomies/hysterectomy, the creation of a neophallus in female-to-male transsexuals, orchiectomies, breast augmentation, facial feminization surgery, the creation of a neovagina in male-to-female transsexuals), with the aim of bringing one’s physical body in line with their felt gender. The ability to transition (socially and medically) are sometimes needed in the treatment of gender dysphoria.

The Endocrine Society does not recommend endocrine treatment of prepubertal children because clinical experience suggests that GID can be reliably assessed only after the first signs of puberty. It recommends treating transsexual adolescents by suppressing puberty with puberty blockers until age 16 years old, after which cross-sex hormones may be given.

The University of Washington is leading the largest study of transgender youth ever conducted. The study, known as the Transgender Youth Project, looks at 300 transgender kids between the ages of 3 and 12. Researchers hope to follow the children for 20 years.

Transsexual people experience a gender identity that is inconsistent with, or not culturally associated with, their assigned sex, and desire to permanently transition to the gender with which they identify, usually seeking medical assistance (including hormone replacement therapy and other sex reassignment therapies) to help them align their body with their identified sex or gender.

"Transsexual" is generally considered a subset of "transgender", but some transsexual people reject the label of "transgender". A medical diagnosis of gender dysphoria can be made if a person expresses a desire to live and be accepted as a member of their identified sex, and if a person experiences impaired functioning or distress as a result of their gender identity.

Transvestic fetishism is a psychiatric diagnosis applied to those who are thought to have an excessive sexual or erotic interest in cross-dressing; this interest is often expressed in autoerotic behavior. It differs from cross-dressing for entertainment or other purposes that do not involve sexual arousal, and is categorized as a paraphilia in the Diagnostic and Statistical Manual of the American Psychiatric Association. (Sexual arousal in response to donning sex-typical clothing is homeovestism.)

Gender dysphoria in children or gender identity disorder in children (GIDC) is a formal diagnosis used by psychologists and physicians to describe children who experience significant discontent (gender dysphoria) with their biological sex, assigned gender, or both.

GIDC was formalized in the third revision of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-III) in 1980 and primarily referenced gender non-conforming behaviors. GIDC remained in the DSM from 1980 to 2013, when it was replaced with the diagnosis of "gender dysphoria" in the fifth revision (DSM-5), in an effort to diminish the stigma attached to gender variance while maintaining a diagnostic route to gender affirming medical interventions such as hormone therapy and surgery.

Controversy surrounding the pathologization and treatment of cross-gender identity and behaviors, particularly in children, has been evident in the literature since the 1980s. Proponents of more widespread GIDC diagnoses argue that therapeutic intervention helps children be more comfortable in their bodies and can prevent adult gender identity disorder. Opponents say that the equivalent therapeutic interventions with gays and lesbians (titled conversion or reparative therapy) have been strongly questioned or declared unethical by the American Psychological Association, American Psychiatric Association, American Association of Social Workers and American Academy of Pediatrics. The World Professional Association for Transgender Health (WPATH) states that treatment aimed at trying to change a person's gender identity and expression to become more congruent with sex assigned at birth "is no longer considered ethical." Critics also argue that the GIDC diagnosis and associated therapeutic interventions rely on the assumption that an adult transsexual identity is undesirable, challenging this assumption along with the lack of clinical data to support outcomes and efficacy.

Gender identity disorder in children is more heavily linked with adult homosexuality than adult transsexualism. According to limited studies, the majority of children diagnosed with GID cease to desire to be the other sex by puberty, with most growing up to identify as gay or lesbian with or without therapeutic intervention.

Transphobia is a range of negative attitudes, feelings or actions toward transgender or transsexual people, or toward transsexuality. Transphobia can be emotional disgust, fear, violence, anger or discomfort felt or expressed towards people who do not conform to society's gender expectations. It is often expressed alongside homophobic views and hence is often considered an aspect of homophobia. Transphobia is a type of prejudice and discrimination similar to racism and sexism, and transgender people of color are often subjected to all three forms of discrimination at once.

Child victims of transphobia experience harassment, school bullying, and violence in school, foster care, and social programs. Adult victims experience public ridicule, harassment including misgendering, taunts, threats of violence, robbery, and false arrest; many feel unsafe in public. A high percentage report being victims of sexual violence. Some are refused healthcare or suffer workplace discrimination, including being fired for being transgender, or feel under siege by conservative political or religious groups who oppose laws to protect them. There is even discrimination from some people within the movement for the rights of gender and sexual minorities.

Besides the increased risk of violence and other threats, the stress created by transphobia can cause negative emotional consequences which may lead to substance abuse, running away from home (in minors), and a higher rate of suicide.

In the Western world, there have been gradual changes towards the establishment of policies of non-discrimination and equal opportunity. The trend is also taking shape in developing nations. In addition, campaigns regarding the LGBT community are being spread around the world to improve acceptance; the "Stop the Stigma" campaign by the UN is one such development.

Sexophobia is the fear of sexual organs or sexual activities and, in a larger sense, the fear of sexuality. As such, it can be applied to the attitude of a person based on his or her educational background, personal experience and psyche, or to the general position of collective entities like religious groups, institutions or states.

Sexophobia in clinical talk has an effect on the way patients speak to their doctors, as it manifests itself in the communication strategies that are employed to speak about private health problems. In that sense, the use of neutral and veiled vocabulary by doctors can discourage patients to speak openly about their sexual issues.

Otherwise, historian and sociologist Cindy Patton has identified sexophobia as one of the main trends that characterised the development of the second phase of the VIH epidemics in Great Britain, along with homophobia and germophobia.

A non-operative transsexual person, or non-op, is someone who has not had SRS, and does not intend to have it in the future. There can be various reasons for this, from the personal to the financial.

Homophobia encompasses a range of negative attitudes and feelings toward homosexuality or people who are identified or perceived as being lesbian, gay, bisexual or transgender (LGBT). It has been defined as contempt, prejudice, aversion, hatred or antipathy, may be based on irrational fear, and is often related to religious beliefs.

Homophobia is observable in critical and hostile behavior such as discrimination and violence on the basis of sexual orientations that are non-heterosexual. Recognized types of homophobia include "institutionalized" homophobia, e.g. religious homophobia and state-sponsored homophobia, and "internalized" homophobia, experienced by people who have same-sex attractions, regardless of how they identify.

Negative attitudes toward identifiable LGBT groups have similar yet specific names: lesbophobia is the intersection of homophobia and sexism directed against lesbians, biphobia targets bisexuality and bisexual people, and transphobia targets transgender and transsexual people and gender variance or gender role nonconformity. According to 2010 Hate Crimes Statistics released by the FBI National Press Office, 19.3 percent of hate crimes across the United States "were motivated by a sexual orientation bias." Moreover, in a Southern Poverty Law Center 2010 "Intelligence Report" extrapolating data from fourteen years (1995–2008), which had complete data available at the time, of the FBI's national hate crime statistics found that LGBT people were "far more likely than any other minority group in the United States to be victimized by violent hate crime."

The term "homophobia" and its usage have been criticized by several sources as unwarrantedly pejorative

Some types of BDSM play include, but are not limited to:

- Animal roleplay

- Bondage

- Breast torture

- Cock and ball torture (CBT)

- Erotic electrostimulation

- Edgeplay

- Flogging

- Golden showers (urinating)

- Human furniture

- Japanese bondage

- Medical play

- Paraphilic infantilism

- Predicament bondage

- Pussy torture

- Sexual roleplay

- Spanking

- Suspension

- Torture

- Tickle torture

- Wax play

In the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), recurrent, intense sexual interest in corpses can be diagnosed under Other Specified Paraphilic Disorder (necrophilia) when it causes marked distress or impairment in important areas of functioning. A ten-tier classification of necrophilia exists:

1. Role players: People who get aroused from pretending their live partner is dead during sexual activity.

2. Romantic necrophiliacs: Bereaved people who remain attached to their dead lover's body.

3. Necrophilic fantasizers: People who fantasize about necrophilia, but never actually have sex with a corpse.

4. Tactile necrophiliacs: People who are aroused by touching or stroking a corpse, without engaging in intercourse.

5. Fetishistic necrophiliacs: People who remove objects (e.g., panties or a tampon) or body parts (e.g., a finger or genitalia) from a corpse for sexual purposes, without engaging in intercourse.

6. Necromutilomaniacs: People who derive pleasure from mutilating a corpse while masturbating, without engaging in intercourse.

7. Opportunistic necrophiliacs: People who normally have no interest in necrophilia, but take the opportunity when it arises.

8. Regular necrophiliacs: People who preferentially have intercourse with the dead.

9. Homicidal necrophiliacs: Necrosadists, people who commit murder in order to have sex with the victim.

10. Exclusive necrophiliacs: People who have an exclusive interest in sex with the dead, and cannot perform at all for living partners.

Though coined as late as the 1910s, the phenomenon is not new. It was referred to in the Hebrew Bible. The word has undergone several changes of meaning since it was first coined and is still used in a variety of senses. Today, the term "transvestite" is commonly considered outdated and derogatory, with the term "cross-dresser" used as a more appropriate replacement. This is because the term "transvestite" was historically used to diagnose medical disorders, including mental health disorders, and transvestism was viewed as a disorder, but the term "cross-dresser" was coined by the transgender community. In some cases, however, the term "transvestite" is seen as more appropriate for use by members of the transgender community instead of by those outside of the transgender community, and some have reclaimed the word.