Sixty preschoolers participated in two experimental sessions designed to measure their beliefs about the relations between effort, interest, and recall as well as their actual effort deployment and recall under different interest levels. In Session 1, children made paired-comparison judgments about the individual and combined effects of high versus low effort and high versus low interest on recall. In Session 2, the children's effort deployment (behavior during study), recall, and attributions for recall in high versus low interest conditions were examined. Findings from Session 1 indicated that the children believed that recall increases with effort and with interest. They also believed that interest influences the amount of effort expended during study such that high interest elicits high effort and leads to superior recall relative to a low interest-low effort combination. Findings from Session 2 indicated that these beliefs were quite naive; that is, interest level did influence the children's effort deployment during study but the effects were more complex than the children had predicted. Contrary to the children's beliefs, effort was not related to recall and recall was superior in the low- not the high-interest condition. Consistent sex differences in beliefs, behavior, and recall performance were found. Compared with boys, most girls held naive beliefs about effort and interest and this naivete was associated with strategic behavior and recall performance advantages. The findings are discussed in terms of the importance and limitations of preschoolers' beliefs about memory.