In some contexts (e.g., legal and medical), it is imperative that children indicate when they do not understand an adult's question. Yet, little research has examined children's clarification requests. We asked 122 4- to 9-year-olds tricky and simple interview questions to assess how often and how children request clarification in interviews, the factors associated with these requests, and whether brief interventions that supplement standard ground rule instructions increase such requests. Overall, the majority of children requested clarification at least once, and most did so explicitly. Child age and question characteristics appeared to influence such requests. Questions that were tricky, especially those that were inaudible or included complex vocabulary/syntax, elicited more clarification requests than simple questions. Supplementing standard ground rule instructions with additional explanations failed to significantly increase clarification requests, though teaching children a clear method for requesting clarification had limited effects on their responses. Results provide insight into children's cognitive development and have implications for interviewing children.