<p>Enhancing genital anatomy literacy and comfort with using correct terminology is a common strategy in sexuality education to promote sexual health and well-being, yet individual variability in these competencies and their links to sexual health and well-being outcomes remain undocumented in young adulthood. This study assessed US emerging adults’ (<i>N</i> = 516; 56.4% cisgender women, 31.3% cisgender men, 12.5% gender-diverse individuals) genital anatomy knowledge—categorizing responses as accurate, slang, unknown, or inaccurate—and their comfort with using correct terminology. It also examined links between knowledge, comfort, and six sexual health and well-being indicators: sexual self-efficacy in health-promoting behaviors, experiencing pleasure, and in refusing unwanted sexual activity; sexual satisfaction, sexual function difficulties, and respectful approaches to sexuality. Knowledge was higher for male (vs. female) anatomical parts and slang use was low overall but more common for male external genitalia. Gender differences emerged in both genital anatomy knowledge and comfort. Controlling for gender, greater knowledge and comfort with genital terminology were associated with higher sexual self-efficacy in health-promoting behaviors and experiencing pleasure, greater sexual satisfaction, and fewer sexual function difficulties. Additionally, comfort predicted resistive self-efficacy, while knowledge predicted more respectful approaches toward a partner. Implications for sexuality education and potential barriers to developing these competencies are discussed.</p>