The purpose of the study was to expand our knowledge of older children's understanding of the unique features and potential relations existing among mental activities. 8- and 10-year-olds as well as adults were asked to rate the similarity of pairs of mental activity scenarios in terms of how their mind would be used for each one. The scenarios involved primarily Prospective Memory, List Memory, Recognition Memory, Comprehension, Inference, Planning, Comparison, or Selective Attention. There was a developing tendency to organize mental activities on the degree to which memory was a component of the activity. Several distinctions were also more likely to be made with age: the distinction between recall and recognition, the distinction between the roles of internal and external cues in mediating cognitive activity, and the distinction among the various roles of attentional processes in regulating input from the sensory world. Together, these findings suggest that a constructivist theory of mind develops in later childhood.