Why do some intimate relationships endure and others do not? Of the stable relationships, why are some couples highly satisfied, whereas other couples become dissatisfied? Vast literatures have focused on theory and research on predictors of relationship stability and satisfaction. In this chapter, we examine how aspects of the sexual relationship are associated with overall relationship satisfaction and stability. We beginwith a focus on the contribution of sexual satisfaction to overall relationship quality and stability. We then discuss how several types of sexual expression, including frequency of sexual activity, sexual communication, and sexual conflict are related to sexual satisfaction and thus also to relationship satisfaction and stability. Although most of the literature conceptualizes sexuality variables as distinct from relationship quality variables (e.g., satisfaction), sexuality is also a component of some relationship phenomena that are empirically and theoretically associated with sexual satisfaction and relationship quality. In this chapter, we also discuss sexuality as a dimension of the following relationship constructs: intimacy, love, exchange, and maintenance behaviors.