Individuals suffering from depressive symptoms tend to be dissatisfied with their romantic relationships, but information is lacking about the mechanisms that link depressive symptoms to relationship quality. This paper evaluates the role of relational uncertainty via an actor—partner interdependence model. Self-report data from 170 romantic partners (N = 85 dyads) revealed that depressive symptoms exerted actor effects, but not partner effects, on relationship quality and relational uncertainty. Moreover, relational uncertainty exerted actor and partner effects on relationship quality. The association between depressive symptoms and relationship quality was mediated by actor effects of self, partner, and relationship uncertainty for women and self uncertainty for men. The paper concludes by discussing how these findings advance scholarship on both relational uncertainty and depression.