Sexualities research is a diverse and wide-ranging field, comprising a variety of theoretical and methodological approaches. Mainstream public health scholars have tended to approach the study of sexualities from an essentialist and biomedical framework, at times drawing on deficit-focused interpretations of sexuality and neglecting questions of power, context, and sexual diversity. Public health researchers have an important role to play in promoting and working toward sexual justice, and critical perspectives and understandings of sexuality are crucial in this regard. Approaching sexualities with a critical lens requires always paying attention to the power relations that shape sexual experiences, identities, and practices. This is of particular urgency in light of the many forms of repression, exclusion, and regressive backlash occurring across the globe, despite the many successes of the struggle for sexual rights and justice. This chapter provides a historical overview of sexualities research in the social sciences and public health and delineates some of the key theoretical trends within sexualities scholarship. It then presents some key priorities for critical research into sexualities within public health that may meaningfully contribute to advancing sexual justice globally.