Background: Childhood obesity is a public health concern that disproportionately affects populations from low socioeconomic status (SES) and minority groups. Evaluation of social and health risk factors of preschool children living along the Texas-Mexico border provides feedback to design health interventions. Methods: South Texas Early Prevention Study-PreK (STEPS-PreK) is a cluster randomized trial designed to assess the effect of the Bienestar coordinated school health program on children's health outcomes. Family characteristics, dietary intake, fitness, and anthropometric data were collected from 1277 preschool students enrolled in 28 preschools. Results: The response rate was 67%. Overall, 57% of families lived in poverty. The mean age of students was 4.7 years, 95% were Hispanic, and 51% were male. The average serving of fruits and vegetables per day were 1 and 1/3, respectively. Of these, students consumed 39.7% of fruits and 18.9% of vegetables. Obesity prevalence for boys was 19.2% and for girls 16.8%. Nearly one-half reported some form of food insecurity. Conclusions: Children living in low-income areas are affected by high levels of social and health risk factors. It is these families who should be targeted with early-age and culturally appropriate health programs.