Risk factors for child obesity may be influenced by family environment, including maternal depression, family structure, and parenting quality. We tested a path model in which maternal depression and single parent status are associated with parenting quality, which relates to three risk factors for child obesity: diet, leisure, and sedentary behavior. Participants included 4,601 5th-grade children and their primary caregivers who participated in the Healthy Passages study. Results showed that associations of maternal depression and single parenthood with child BMI are mediated by parenting quality and its relation to children's leisure activity and sedentary behavior. Interventions for child obesity may be more successful if they target family environment, particularly parenting quality and its impact on children's active and sedentary behaviors. © 2010 The Obesity Society.