This dissertation proposes and explores the construct of “gender pleasure,” or the positive affective experience of gender/sex. Although much of the research in psychology concerns the negatives of gender/sex, such as sexism, transphobia, and gender dysphoria, gender pleasure highlights how gender/sex can also be a source of joy and affirmation. In Chapter 1, I situate this dissertation within gender/sex research in psychology, particularly research centering gender/sex diversity and gender/sex as a social process. I then review literature relevant to people’s positive gender/sex experiences, particularly for people minoritized on the basis of their gender/sexes and/or sexualities. In Chapter 2, I describe a study that aimed to explore “gender euphoria,” a term related to gender pleasure that originated within gender/sex minority communities as a positive contrast to gender dysphoria. Despite gender euphoria’s importance to many people, no psychological research had directly explored this term’s meanings and related experiences. I therefore administered a qualitative survey to community members (N = 47) about where they had heard the term being used, how they would define gender euphoria and gender dysphoria, the relation between these terms, and their gender euphoric experiences. Analyses generated five themes: (1) gender euphoria describes a joyful feeling of rightness in one’s gender/sex, (2) gender euphoric experiences can be external, internal, and/or social, (3) “gender euphoria” originated in and circulates in online and in-person gender/sex minority communities, (4) dysphoria describes a negative feeling of conflict between gender/sexed aspects of one’s self, and (5) the relationship between euphoria and dysphoria is complex. I conclude that these results can inform qualitative and quantitative research, gender affirmative clinical practice, political fights for transgender rights, and understandings of gender/sex experiences for people of many identities. In Chapter 3, I describe my second study that extended understandings of gender pleasure beyond gender euphoria. To do this, I conducted focus groups with gender/sex/ual minorities diverse in terms of race/ethnicity (N = 64). Analyses generated four themes: (1) Accepting one’s self and living in authenticity and freedom provide joy, relief, and comfort; (2) Interpersonal gendered experiences that are affirming and free from judgement provide validation and belonging; (3) Gender norms and intersecting social locations and systems of power shape experiences of gender pleasure; and (4) Gender pleasure involves purely positive experiences, relief from negative experiences, and increases in positive affect. These results have implications for positive psychology research with gender/sex/ual minorities, thinking of gender/sex as a process, and clinical practice. In Chapter 4, I propose a model of gender pleasure as resonance between people’s gender/sex orientations, identities, and statuses (van Anders, 2015). I also demonstrate how the study of gender pleasure can contribute to gender/sex diversity research and more by attending to the ways gender/sex/ual minorities find enjoyment and happiness within their gender/sexes despite oppression. I conclude with the many potential avenues that this dissertation opens for understanding gender/sex in more comprehensive ways, ultimately in service of supporting the flourishing of people of all gender/sexes and sexualities.