Intervention to enhance Interpersonal Cognitive Problem Solving (ICPS) skills has been shown to significantly reduce observable negative, impulsive and inhibited behaviors and increase positive qualities in young, low socioeconomic status (SES) children. An ICPS model for older children was implemented with 202 low SES fifth graders to test whether ICPS skills function as significant behavior mediators at that age. A series of 55 age-appropriate lesson-games were created for use by classroom teachers to enhance students' ability to apprehend the perspective of others (role-taking) and their problem solving skills. These skills included alternative solution thinking, consequential thinking, and means-ends thinking. The findings following 15 weeks of training indicated that overall gains in ICPS, but not multiple perspective-taking scores, correlated with gains in behavior, and most consistently with positive, prosocial behaviors in both boys and girls. In both sexes, it was an improvement in number and range of solutions that best related to these behavior gains, and most consistently to teacher ratings of concern for others, peer sociability, and the degree to which the child was liked by peers. In boys only, gains in consequential and means-ends skills also related to prosocial change. ICPS linkage gains with negative, aberrant behaviors were less clear and, while ICPS gains did not link with academic gains, prosocial behavior gains did. (NRB)