Objectives. We sought to better understand the prevalence and consequences of food insecurity among American Indian families with young children. Methods. Parents or caregivers of kindergarten-age children enrolled in the Bright Start study (dyad n = 432) living on the Pine Ridge Reservation in South Dakota completed a questionnaire on their child's dietary intake, the home food environment, and food security. We assessed food security with a standard 6- item scale and examined associations of food insecurity with family sociodemographic characteristics, parents' and children's weight, children's dietary patterns, and the home food environment. Results. Almost 40% of families reported experiencing food insecurity. Children from food-insecure households were more likely to eat some less healthful types of foods, including items purchased at convenience stores (P = .002), and food-insecure parents reported experiencingmany barriers to accessing healthful food. Food security status was not associated with differences in home food availability or children's or parents' weight status. Conclusions. Food insecurity is prevalent among families living on the Pine Ridge Reservation. Increasing reservation access to food that is high quality, reasonably priced, and healthful should be a public health goal.