Because ambiguity is a fundamental property of the human language, children need to develop the ability to resolve ambiguities online in order to efficiently understand spoken language and to acquire the meanings of words. However, very little is understood about the cognitive mechanisms underlying the processing of ambiguous words during sentence comprehension in children. In this project, we will study how children and adults constrain their interpretation of word meanings in situations requiring them to evaluate multiple possible interpretations for a word. For instance, when listening to a homophonous word such as “flies” in a sentence like “the baby flies” is a child (or an adult) able to consider the two possible interpretations for the word “flies”: the insects (flies) and the action (to fly)? If they initially select the wrong interpretation, how do they switch from one interpretation to another? This project will investigate whether the ability to resolve syntactic ambiguities relies on a mechanism of parallel vs. selective access of possible interpretations for an ambiguous word and/or a mechanism that should adjust the reliance on different sources of information during sentence processing. In a first part of this project will examine what is the time course of mental access to possible meanings during ambiguity resolution, asking whether children have parallel access to all the possible meanings for an ambiguous word during sentence processing, or whether word meaning activation is restricted to a selective access of one possible meaning at a time depending on the syntactic structure of sentences. In a second line of research, we will examine how children choose the cues that might be relevant or irrelevant to solve syntactic ambiguities and whether they can be encouraged to deal flexibly with the input and to change the importance that they attribute to certain linguistic cues depending on the context. The combination of the studies outlined in this project should reveal how children figure out meanings for ambiguous words in context, and how stored linguistic knowledge and expectations shape information processing in real time. Understanding how humans develop the ability to resolve ambiguities and the cues that they use to constrain their interpretations is extremely important to understand the mechanisms underlying human language acquisition. This project will provide important experimental results that will further our understanding of human development and the mechanisms underlying language acquisition.