Studies showing that early language skills are important predictors of later academic success and social outcomes have prompted efforts to promote early language development among children at risk. Good social skills, a competence identified in many children who are English Language Learners (ELLs), have been posited in the general literature as facilitators of language development. Yet to date, a comprehensive review on the nature and impact of social interaction on language development among children who are ELLs has not been conducted. Using PRISMA procedures, a systematic review was conducted and 10 eligible studies published between 2008 and 2019 were identified. Findings revealed that despite their limited language capabilities, children who are ELLs can engage in complex speech during peer interaction. However, the nature and frequency of interactions, as well as the unique skill sets of communication partners may affect their development of relevant language skills. These findings have implications for policy and intervention development for preschool settings in the United States. (author abstract)