ABSTRACTAmid adolescence, youth are developing the relational skills necessary to form and maintain positive intimate relationships. Sexual assertiveness is a key skill that could be related to couples’ sexual outcomes (i.e. sexual satisfaction, sexual concerns, and sexual function). However, dyadic studies are lacking, and associations between sexual assertiveness and adolescents’ sexual health and well-being remain underexplored. This cross-sectional dyadic study examined associations between dimensions of sexual assertiveness and sexual outcomes in adolescent romantic relationships. The Actor-Partner Interdependence Model guided analyses of self-reported questionnaires from 110 romantic dyads (aged 14–19 years; M = 16.51). Participants’ gender was considered in the models, and gender differences emerged in the associations between study variables. Path analyses revealed that sexual needs and desires communication, refusal of unwanted sex, sexual intimacy initiation, and comfort talking about sex have significant actor and partner effects on adolescents’ sexual outcomes in mixed-gender dyads. These findings suggest that authentically expressing one’s own sexual needs, desires, and limits in adolescence may influence not only one’s own sexual satisfaction, sexual concerns, and sexual function, but also their partner’s. The aforementioned dimensions of sexual assertiveness could be important targets for research-based interventions to promote sexual health and well-being in adolescent romantic relationships.