This study examined the ability of 2 1/2-4 1/2-years-olds to recognize comprehension difficulties and to implement strategies for resolving them. In the course of a play interaction, an adult female experimenter made a series of requests, some of which were designed to be difficult for the child to understand or to execute. Children's responses to these requests were compared with their responses to control requests that were easy to comprehend and comply with 3-year-olds exhibited appropriate and selective monitoring responses for some kinds of problems but not others, while 4-year-olds displayed discriminative monitoring for all types of problems presented. In contrast to previous experimental findings, these results indicate that young children are capable of detecting a variety of comprehension problems and possess appropriate strategies for resolving these difficulties with a partner in communication.