The past several decades has witnessed an explosion of research on the intimate relationships of sexual minorities (i.e., individuals with same-sex attractions or behaviors) and gender minorities (i.e., individuals whose gender identities or presentations deviate from conventional gender norms). This chapter provides a review of this growing body of research. Although sexual minorities and gender minorities are distinct populations with distinct relationship experiences, we address both populations in this chapter because they face similar challenges regarding social marginalization, and because their experiences highlight the complex ways in which sexual identity, gender identity, and social stigma inform a range of intimate relationship processes. Topics covered include the stress associated with sexual-minority and/or gender-minority status, basic relationship processes such as initiation and formalization (including legal marriage), sexual behavior, gender-related norms within relationships, and intimate partner violence. We conclude by highlighting directions for future research, such as greater attention to within-person variation in relationship experiences over time and greater attention to processes of resilience in marginalized individuals and couples.