Successful family-based weight loss interventions for African American adolescents are rare. Parent-adolescent interactions supporting adoption of healthier nutrition and physical activity practices are not well understood. African American caregivers' and adolescents' perspectives on how they worked together to achieve weight loss need further exploration. This study describes the relationships experienced by adolescents and caregivers during the 6-month, evidence-based FIT Families weight loss trial and explores differences between families whose adolescents were successful and unsuccessful with weight loss. Exit interviews conducted with 136 adolescents (age 12–16 years; BMI percentile ≥95) and their caregivers (primarily mothers) were taped and transcribed verbatim. Content and thematic analysis was conducted to explore differences between groups stratified by weight loss. Five adolescent-caregiver relationship patterns emerged which describe dyads working together, working alone, working against each other; caregiver support and caregiver working on self. When relationship patterns were compared between groups stratified by weight loss, three themes emerged: motivation, support, and persistence. Families that achieved the greatest weight loss referred more often to working together to reach weight loss goals, attributed their success to adolescent self-motivation, with engaged caregiver support which allowed families to persist in change efforts. Family relationships involving adolescent autonomy, engaged parental support, and persistence despite challenges, clustered differently among adolescents who were successful at weight loss compared to those who were not. Interventionists trained to reinforce effective adolescent-parent interactions will advance behavioral interventions for families who have typically benefited least in prior interventions.