Home and preschool are central contexts for children’s language development. However, the child’s language environment—adult speech around the child, the child’s own speech production, and conversational turns between the child and adults—is rarely compared between these contexts. Furthermore, we know little about potential differences between children with and without autism spectrum disorder (ASD) in the two contexts. We used objective measures of vocalizations to quantify children’s real-time dyadic vocal interactions. Participants included 11 preschoolers in an inclusive classroom, observed both at home and in preschool. Overall, there were no significant differences in child vocalizations, conversational turns, and adult word counts between preschool and home. However, children with ASD exhibited larger effects of context—having higher rates of conversational turns at home than in preschool—than other children. Findings highlight the interaction between children’s developmental characteristics and the external environment as drivers of language environment in early childhood.