To examine the developmental changes on the Children's Form of the Picture-Frustration (P-F) Study, the instrument was administered to 291 children between the ages of 6 and 13, from two schools. Developmental changes in the 11 response types were compared with changes in the six aggression category scores, which were combinations of the 11 response types. In contrast to the findings for the aggression categories, changes in the response types were consistent with developmental research on children's aggression. The findings supported the validity of the P-F Study as a measure of children's thought content in response to frustration and supported previous research indicating that the response types may be more meaningful data from the instrument than from the aggression category scores.