ABSTRACT Purpose This study sought to understand family functioning surrounding weight in Mexican American women with obesity. Methods Semi-structured in-depth interviews were conducted with mothers and adult daughters (N = 116). Results Thematic analysis identified five themes. 1) The communication process drives perception of supportive messages. Messages perceived as non-supportive consist of directives as interventions, confirmation of faults, and critical compliments whereas supportive consist of compliments, encouragement, empathetic listening, and disclosure. 2) Acculturation differences interfere with intergenerational alliance. Differences involve dissonance in communication, behavioural expectations, and weight-related practices. 3) Maladaptive conflict responses contribute to relational strain. These responses include avoidance, withdrawal, and defensiveness. 4) Role transformations alter the generational hierarchical relationship. Daughters serve as role models, caregivers, or collaborators. 5) Low communal coping heightens psychological distress. It does so by challenging family roles, increasing social isolation, and compromising social support. Conclusion Obesity interventions for Mexican American women may benefit from targeting relational skills to improve family functioning.