This study tested an actor-partner interdependence mediation model (APIMeM) in which dyadic relational maintenance behaviors (RMBs) mediate the relationship between romantic attachment (i.e., anxious and avoidant) and multiple indicators of relationship quality among couples in long-distance relationships (LDRs). Data were collected from 137 couples (women’s mean age = 20.37 years; men’s mean age = 21.93) who were in a serious romantic LDR and who completed an attachment measure, a measure of dyadic RMBs, and four measures of relationship quality (i.e., relationship satisfaction, relational commitment, closeness with the partner, and connection with others). Path analyses revealed significant actor and partner effects. Moreover, a total mediation between women’s anxious attachment and both partners’ relationship quality, and a partial mediation between men’s and women’s avoidant attachment and their own relationship quality were uncovered. Overall, the results suggest that, for couples in LDRs, one partner’s behaviors, cognitions, or emotions influence each member of the dyad as well as the quality of the relationship.