The prevalence of overweight and obesity among Mexican-American children is exceedingly high. Understanding the role of mobile food vendors in low-income, limited-resource Mexican-American colonia neighborhoods is critical. With the involvement of community partners and building on prior food environment projects within the colonias, the aim of this study is to assess the neighborhood and household food environments, current food and beverage marketing and purchase strategies for after-school and weekend consumption, as well as seasonal patterns, and current family food behaviors, in a sample of Mexican-American mother-child dyads. Results of this study will enable the implementation of public policies targeted at the dietary intake of Mexican-American children in the colonias by determining the contribution of traditional snack foods supplied by mobile food vendors to the overall dietary intake of colonia children.