This research examined two questions: effects of deception on children's understanding of second-order false belief, and possible effects of number of siblings on second-order performance. Kindergarten children responded to 3 second-order problems that varied in the presence and the nature of deception. Performance was better on the problems with deception, but significantly so only when the target for the belief attribution produced the deception. This finding helps to clarify differences between the two main paradigms for assessing second-order false belief. There was no relation between number of siblings and performance.