Objective: This study investigated the actor and partner effects of self-esteem on the quality of the parental couple relationships: the romantic relationship and the coparental relationship. The mediating role of romantic quality also was considered. Background: Previous findings suggest that self-esteem affects the quality of the romantic relationship. Yet few studies have focused on self-esteem in the parental couple or explored self-esteem related to the coparental relationship, both of which play a significant role in the nature of the family unit. Method: Using data from two independent samples (including 2,549 couples), actor-partner interdependence models were tested to analyze the effects of self-esteem on both relationships of the parental couple. Results: Parents with high self-esteem reported higher romantic quality, as did their partner. Self-esteem also showed actor and partner effects on negative coparenting. Accordingly, parents with high self-esteem reported fewer conflicts about the child and fewer undermining behaviors. In contrast, the link between self-esteem and positive coparenting received little support. However, when mothers had high self-esteem, they engaged more frequently in positive coparental behaviors, such as including the father. Finally, romantic relationship quality mediated the actor and partner effects of self-esteem on negative coparenting. Conclusion: Having high self-esteem appears to be a couple resource with beneficial effects for both parents. Implications: Improving parents' self-esteem could be an important gateway for enhancing the functioning of families with romantic and coparental difficulties.