Sexual identity is how one thinks of oneself in terms of whom one is romantically or sexually attracted to. Sexual identity may also refer to sexual orientation identity, which is when people identify or dis-identify with a sexual orientation or choose not to identify with a sexual orientation. Sexual identity and sexual behavior are closely related to sexual orientation, but they are distinguished, with identity referring to an individual's conception of themselves, behavior referring to actual sexual acts performed by the individual, and sexual orientation referring to romantic or sexual attractions toward persons of the opposite sex or gender, the same sex or gender, to both sexes or more than one gender, or to no one.
Historical models of sexual identity have tended to view its formation as a process undergone only by sexual minorities, while more contemporary models view the process as far more universal and attempt to present sexual identity within the larger scope of other major identity theories and processes.
Definitions and identity
Sexual identity has been described as a component of an individual's identity that reflects their sexual self-concept. The integration of the respective identity components (e.g. moral, religious, ethnic, occupational) into a greater overall identity is essential to the process of developing the multi-dimensional construct of identity.
Sexual identity can change throughout an individual's life, and may or may not align with biological sex, sexual behavior or actual sexual orientation. For example, gay, lesbian, and bisexual people may not openly identify as such in a homophobic/heterosexist setting or in areas whose record on LGBT rights is poor. In a 1990 study by the Social Organization of Sexuality, only 16% of women and 36% of men who reported some level of same-sex attraction had a homosexual or bisexual identity.
Sexual identity is more closely related to sexual behavior than sexual orientation is. The same survey found that 96% of women and 87% of men with a homosexual or bisexual identity had engaged in sexual activity with someone of the same sex, as contrasted to 32% of women and 43% of men who had same-sex attractions. Upon reviewing the results, the organization commented: "Development of self-identification as homosexual or gay is a psychological and socially complex state, something which, in this society, is achieved only over time, often with considerable personal struggle and self-doubt, not to mention social discomfort."
Most of the research on sexual orientation identity development focuses on the development of people who are attracted to the same sex. Many people who feel attracted to members of their own sex come out at some point in their lives. Coming out is described in three phases. The first phase is the phase of "knowing oneself," and the realization emerges that one is sexually and emotionally attracted to members of one's own sex. This is often described as an internal coming out and can occur in childhood or at puberty, but sometimes as late as age 40 or older. The second phase involves a decision to come out to others, e.g. family, friends, and/or colleagues, while the third phase involves living openly as an LGBT person. In the United States today, people often come out during high school or college age. At this age, they may not trust or ask for help from others, especially when their orientation is not accepted in society. Sometimes they do not inform their own families.
According to Rosario, Schrimshaw, Hunter, Braun (2006), "the development of a lesbian, gay, or bisexual (LGB) sexual identity is a complex and often difficult process. Unlike members of other minority groups (e.g., ethnic and racial minorities), most LGB individuals are not raised in a community of similar others from whom they learn about their identity and who reinforce and support that identity" and "[r]ather, LGB individuals are often raised in communities that are either ignorant of or openly hostile toward homosexuality."
Some individuals with unwanted sexual attractions may choose to actively dis-identify with a sexual minority identity, which creates a different sexual orientation identity from their actual sexual orientation. Sexual orientation identity, but not sexual orientation, can change through psychotherapy, support groups, and life events. A person who has homosexual feelings can self-identify in various ways. An individual may come to accept an LGB identity, to develop a heterosexual identity, to reject an LGB identity while choosing to identify as ex-gay, or to refrain from specifying a sexual identity. In a The Wall Street Journal article on reconciling faith and homosexuality, researcher Judith Glassgold, who chaired the task force, stated, "We're not trying to encourage people to become ex-gay’" and "there has been little research on the long-term effects of rejecting a gay identity, but there is 'no clear evidence of harm' and 'some people seem to be content with that path'".
Models of sexual identity development
Several models have been created to describe coming out as a process for gay and lesbian identity development (e.g. Dank, 1971; Cass, 1984; Coleman, 1989; Troiden, 1989). These historical models have taken a view of sexual identity formation as a sexual-minority process only. However, not every LGBT person follows such a model. For example, some LGBT youth become aware of and accept their same-sex desires or gender identity at puberty in a way similar to which heterosexual teens become aware of their sexuality, i.e. free of any notion of difference, stigma or shame in terms of the gender of the people to whom they are attracted. More contemporary models take the stance that it is a more universal process. Current models for the development of sexual identity attempt to incorporate other models of identity development, such as Marcia’s ego-identity statuses 
The Cass identity model, established by Vivienne Cass, outlines six discrete stages transited by individuals who successfully come out: (1) identity confusion, (2) identity comparison, (3) identity tolerance, (4) identity acceptance, (5) identity pride, and (6) identity synthesis. Fassinger's Model of Gay and Lesbian Identity Development contains four stages at the individual and group level: (1) awareness, (2) exploration, (3) deepening/commitment, and (4) internalization/synthesis.
Some models of sexual identity development do not use discrete, ordered stages, but instead conceptualize identity development as consisting of independent identity processes. For example, D'Augelli's model describes six unordered independent identity processes: (1) exiting heterosexual identity, (2) Developing personal LGB identity status, (3) Developing a LGB social identity, (4) Becoming a LGB offspring, (5) Developing a LGB intimacy status, and (6) Entering a LGB community.
Contemporary models view sexual identity formation as a universal process, rather than a sexual minority one  in that it is not only sexual minorities that undergo sexual identity development, but heterosexual populations as well. More recent research has supported these theories, having demonstrated that heterosexual populations display all of Marcia’s statuses within the domain of sexual identity.
- Androphilia and gynephilia
- Erikson's stages of psychosocial development
- Men who have sex with men
- Questioning (sexuality and gender)
- Situational sexual behavior
- Women who have sex with women
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Sexual orientation identity—not sexual orientation—appears to change via psychotherapy, support groups, and life events.
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- The End of Sexual Identity: Why Sex Is Too Important to Define Who We Are (2011) Jenell Williams Paris