In the United States, children from diverse ethnic groups and those with low socioeconomic status are at a significantly increased risk for early childhood caries. Despite the efforts focused on decreasing early childhood caries in American Indian (AI) populations, these children have the highest incidence of dental caries of any ethnic group, with four times the cases of untreated dental caries compared to white children. This qualitative formative assessment was conducted in two AI communities. Semi-structured interviews (n = 57) were conducted with caregivers and providers to understand the social and community contexts in which oral health behaviors and practices occur from the perspective of the caregivers, oral health care providers, and social service providers in the communities. The analysis was informed by the social determinants of health framework. The key social determinants of pediatric oral health relevant to our study communities included limited access to: oral health promoting nutritious foods, transportation for oral health appointments, and pediatric specialty care. This formative assessment provided locally and contextually relevant information to shape the development of an oral health clinical trial intervention to address early childhood caries in these two communities.