The purpose of this research is to investigate the effectiveness of a community health worker-based program as an adjunct to clinical services regarding childhood obesity management. This family-centered program will be delivered in the community and homes of enrolled families. The primary outcome will compare change in age-gender specific body-mass-index (BMI) z-score (zBMI) over time. All Denver Health children and families will be enrolled at study inception and receive the intervention in 1 of 5 defined 6-month stepped wedge engagements. The intervention lasts for 6 months and the time prior to engagement in the intervention will serve as the control period. Intervention construct validity will be evaluated using data on diet, activity, and fitness. The primary goal is to examine the effect of the intervention in reducing the zBMI in the index patient and secondarily on any participating family members. We will test effectiveness among demographic groups under-represented in prior studies, including very young children and Latinos. Results from this study will inform future intervention modifications and permit effect size estimation and power calculations for future randomized trials that include a community health worker-based obesity prevention and treatment program. During the course of the study, an obesity registry will be designed and implemented within an integrated safety-net healthcare system to measure primary obesity outcomes in a low-income population and conduct analyses. The community health worker will be using several new technologies (e.g., text messaging and patient relationship manager [PRM]) as an adjunct when working with an obese child and his/her family. Targeted training for clients, providers and CHW will be part of the prevention strategies implemented during the grant period, these will include motivational interviewing. All of these (i.e., obesity registry, technologies and training) will have an evaluative component.