Few researchers have investigated the factors that influence children's tendency to indicate correctly when they do not know the answer to a question. In this study, 5- to 8-year-olds witnessed a staged event in their classroom and were subsequently interviewed about that event either the following day or after 5 months. Some of the questions were answerable based on the information in the event, and some were unanswerable such that children would have had to guess to provide an answer. Individual-difference measures were taken of children's verbal ability and self-perceptions. Delay, verbal ability, and children's self-perceptions all affected whether children correctly indicated when they did not know the answer to a question. (Contains 3 tables and 1 footnote.)