Mexican American families share similar elevated risks for obesity and obesity-related conditions, such as type 2 diabetes. Because negative family interactions and relationships (e.g., poor communication, high conflict, low emotional closeness) are associated with obesity treatment outcomes, this study tests a behavioral weight management intervention that provides relationship skills counseling to mothers and adult daughters. The goal is to improve family interaction patterns to buffer challenges and strengthen collaboration for eating and physical activity behaviors that support long-term weight management and thus provide an effective obesity treatment approach to address a major public health concern.