PROJECT SUMMARY/ABSTRACT Language ability is often impaired in children with autism spectrum disorder (ASD). Language ability in the preschool years is a powerful predictor of outcomes. In these early years, parents are a primary source of early language. It is therefore crucial to study the language input that parents of children with ASD provide and children's abilities to comprehend and learn from that input. In the current proposal, we study how preschoolers with ASD and typically- developing (TD) peers assign meaning to the language they hear, and how parental language input supports these efforts. More specifically, our goal is to understand how children learn the meanings of new words. We focus on verbs because the sentence contexts in which unfamiliar verbs are heard provide helpful information for TD children to acquire their meaning. However, we know little about what kinds of sentence contexts are most useful in ASD, or about what kinds of contexts parents provide in their own speech. To pursue this issue, we present children with unfamiliar words either in carefully constructed linguistic contexts, varying how informative and easy-to-process they are, as well as the number of repetitions of each context (Study 1) or unscripted sentence contexts produced by their own parent (Study 2). We use eye-tracking measures to assess how children understand the contexts and assign the words a meaning. This research will shed light on the mechanisms underlying language learning in ASD and in TD and will support the development of effective language interventions, including parent-based interventions.