Project Summary Child obesity disproportionately impacts young Latino children. Obesity interventions focusing on 2- to 5- year-olds are critical as excessive weight gain during this period increases the risk of adolescent and adult overweight and has important implications for later health problems. Moreover, many obesogenic behaviors in adulthood, like television viewing and consumption of sugary drinks, begin at this age. The most effective childhood obesity interventions are those rooted in behavior and family systems theories. Both of these theories provide approaches to support lifestyle changes with an understanding that family is the major mediator of social influences on a child’s development. To date, however, most family-based interventions: (1) focus on one parent, typically mothers; (2) miss the opportunity to leverage the Latino cultural value of familism (i.e. family connectedness) to impact childhood obesity outcomes; and (3) include lengthy curricula requiring weekly in-person sessions over a 2- to 6-month time period. The rationale for the proposed study is to address these shortcomings by evaluating the effectiveness of a community-based intervention that is shorter and involves multiple family caregivers. The intervention will include in-person and mobile phone components focusing on Latino caregivers of young children, to support evidence-based and age appropriate dietary, media-viewing, and physical activity practices among 2- to 5-year old children, in order to decrease ethnic disparities in childhood obesity. The study will also explore the intervention’s potential to multiply the public health benefit by reducing obesity risk for adult caregivers. A prospective randomized study design will be used to evaluate the effectiveness of the family-based childhood obesity intervention on child BMI at 6- months (primary outcome) and at 12 months (secondary outcome), compared to a usual WIC care group. The study will randomize approximately 260 adult Latino caregivers of 2- to 5-year old children (2 caregivers per child) and half will be assigned to the intervention, and the other half will serve as the control group. All families will be recruited from four WIC Centers in Los Angeles County. Primary and secondary outcomes will include: (1) changes in child BMI outcomes at 6- and 12 months; (2) changes in child dietary, media-viewing, and physical activity practices; (3) whether familism attenuates or amplifies the intervention’s effect on differences in child BMI change between intervention and WIC usual care group; and (4) changes in caregiver’s dietary, physical activity, and weight. Pre- and post-intervention anthropometric and survey data will be collected at baseline, 1-, 6-, and 12-months post-baseline to estimate the intervention effect size on child BMI and weight-related practices, and explore whether familial mechanisms moderate the intervention’s effect on child BMI.