Attrition in pediatric weight management is a substantial problem. This study examined factors associated with short- and long-term attrition from a lifestyle and behavioral intervention for parents of children with overweight or obesity.Fifty-two families with children ages 6 to 12 years old and body mass index at or above the 85th percentile participated in a randomized controlled trial focused on parents, comparing parent-based cognitive behavioral therapy with parent-based psychoeducation for pediatric weight management. We examined program attrition using two clinical phases of the intervention: short-term and long-term attrition, modeled using the general linear model. Predictors included intervention type, child/parent weight status, sociodemographic factors, and health of the family system.Higher self-assessed health of the family system was associated with lower short-term attrition; higher percentage of intervention sessions attended by parents was associated with lower long-term attrition.Different variables were significant in our short- and long-term models. Attrition might best be conceptualized based on short- and long-term phases of clinical, parent-based interventions for pediatric weight management.