This chapter presents how socioeconomic status (SES) shapes children's language learning environments and their language development, in the larger context of how SES shapes children's lives and developmental trajectories. The literature provides ample evidence that both the environments in which children acquire language and the rate of children's language development vary as a function of family SES. Environmental differences arise from SES-related differences in the ways in which mothers interact with and talk to their children. Compared to lower-SES mothers, higher-SES mothers talk more to their children and are more responsive to their children's verbalizations. The chapter seeks to explain how SES has the effects on language environments and language development. It describes the SES-related differences in language environments and child language observed in one sample of mid- and high-SES families in the midwestern United States. The chapter investigates hypothesized processes that link SES to language environments and developmental outcomes.