Using confirmation theory, this study investigated how romantic couples' (N = 100) accepting and challenging communication was associated with several weight management (WM) outcomes (i.e., partners' general effectiveness in motivating each other to enact healthy behaviors, productivity of WM conversations, and diet and exercise behaviors). Actor-partner interdependence model analyses showed that acceptance and challenge from partners simultaneously predicted how effective partners were in motivating healthy behaviors, but these components of confirmation predicted the other outcomes in different ways. Analyses across the outcomes also revealed that similar partner communication styles predicted general effectiveness, more productive WM conversations, and healthier eating habits. The findings of this study highlight the importance of assessing the interdependence of partners' WM efforts.