Project Summary Child obesity disproportionately impacts young Latino children and has important implications for later adulthood weight and health problems. In-person parent-focused obesity prevention and control interventions are effective in establishing healthy weight behaviors and weight outcomes for young children, including Latino children. Widespread dissemination in healthcare and community settings pose several challenges including family participation barriers of time, cost, transportation, and English proficiency. The study goal is to pilot a stand-alone mobile phone intervention with Latino mothers, fathers, and grandparents, geared at building caregiver strategies to support evidence-based and age appropriate dietary, media-viewing, and physical activity practices among 2- to 5-year old children in order to resolve key challenges of traditional in- person pediatric obesity interventions (e.g. transportation, time), and also leverage important determinants of Latino health (e.g. familism, language). A prospective control group pilot study will be completed to assess acceptability, feasibility, and preliminary effect sizes on children's weight-related behaviors and BMI z-scores at 6 months post-intervention, in preparation for a larger randomized trial to evaluate the intervention's efficacy. The intervention will deliver 4 interactive texts every week for one month to Latino caregivers of 2 to 5-year old children and 2-months of mobile phone ?booster? doses that incorporate behavioral change techniques using a group strategy, a cornerstone of many effective in-person parent-focused pediatric obesity interventions. The study will first use qualitative methods to maximize the acceptability and usability of the existing mobile phone group learning strategies with a small group of Latino mothers, fathers, and grandparents. A 4-week mobile phone pilot intervention will then be completed with 66 caregiver-child dyads recruited from two WIC sites in East Los Angeles. Eligible caregiver-child dyads will be randomly assigned into the mobile phone intervention group or the comparison group, in which caregivers receive usual WIC services. Acceptability and feasibility outcomes will include: (1) the number of families needed to be screened per month; (2) attrition rates of a mobile phone intervention with Latino populations; (3) dose and exposure of texts; (4) frequency of sharing/replying to texts by caregiver-type; (5) number of completed baseline and follow-up data; and (6) family-centeredness of the intervention. Pre- and post- intervention data will be collected at baseline, 1-month, and 6-months after the intervention begins in order to estimate preliminary effect sizes and standard deviations associated with child dietary, physical activity, and media viewing practices and BMI scores. Mediators of the intervention will include measures of caregiver self-efficacy, caregiver feeding practices, and group support. The pilot study will provide the acceptability, feasibility, and preliminary data on child weigh-related behaviors and BMI to develop an R01 proposal to test the intervention's effectiveness via a randomized controlled trial.