Objectives.This study examined the ways in which body mass index (BMI) percentile – an identified risk factor for overweight and cardiovascular disease in adulthood – develops from birth through early adolescence. In addition, we examined whether psychosocial factors, such as parenting style and maternal depression, mediated the link between socio‐economic status (SES) and BMI growth.Design.Data were obtained from phases 1–3 of the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care and Youth Development (SECCYD) – a longitudinal study that followed children from 10 communities in the United States from birth to age 11.Methods.We applied growth mixture models to identify distinct subtypes of BMI development. Within these models, we performed between‐ and within‐class mediation analyses to examine whether SES predicted class membership or differences in development within each class via maternal depression and parenting styles.Results.Results identified three prototypic trajectories of BMI percentile growth,elevated,steady increase, andstable. We found evidence for both between‐ and within‐class mediation, suggesting multiple pathways by which SES can affect BMI development.Conclusions.These findings add to the research that suggests that being in a family with a low SES is associated with falling into patterns of development characterized by early and lasting increases in BMI relative to one's peers, and that this association is partly accounted for by maternal depression and parenting styles.Statement of ContributionWhat is already known?Past research has found evidence that patterns of childhood overweight are impacted by socioeconomic status through psychosocial factors like parenting and depression. This evidence is often limited to individual points in time where neglectful, permissive, and authoritarian parenting and higher levels of maternal depression are associated with higher levels of overweight status among children from infancy to adolescence. However, little research has linked together whether the children who receive non‐authoritative parenting and are overweight in infancy are the same children who are overweight in adolescence.What does this study add?• Evidence for 3 different prototypes of BMI percentile growth over the course of childhood approaching adolescence.• Adds complexity re the influence of parenting styles as an influence on patterns of weight gain.• Buttresses existing research as to early and lasting ef