The 21st century has seen shifts in social and scientific understandings of gender and sexuality in the United States. From the legitimization of same-sex marriage to the heightened visibility of transgender identities, nonbinary gender, and forms of intimate diversity such as asexuality, kink, and polyamory, core cultural and scientific assumptions about gender and sexuality have been challenged. This article situates these changes in the historical context of 21st century social technologies, which challenge traditional sources of authority about information and provide enhanced opportunities for individuals to experience authenticity in gender and sexuality. We frame authenticity as a master cultural narrative in the United States characterized by feeling a heightened sense of self-authorship and alignment between inner experience and embodiment of gender and sexuality. Five narratives now circulate in the United States, four of which support sexual and gender diversity: (a) gender as self-constructed; (b) sexuality as plural, playful, flexible, and fluid; (c) sexuality and monogamy as cultural compulsions; and (d) intersectionality as central to the experience of sexuality and gender. A fifth narrative seeking to legitimize hierarchies (e.g., patriarchy) is hostile to sexual and gender diversity but remains anchored in a metanarrative of authenticity and has benefitted equally from the affordances of social technologies. This historical moment provides researchers and practitioners with the opportunity to more intentionally ground their work in lived experience, challenge normative thinking about sexuality and gender, practice affirmation, center the phenomenon of diversity over discrete identity categories in an ever-exclusionary acronym (lesbian, gay, bisexual, transgender, queer/questioning, and more identities [LGBTQ+]), and embrace fluid and nonlinear narratives of social change. (PsycInfo Database Record (c) 2025 APA, all rights reserved).