Prosocial behavior was assessed at ages 12–14 and 15–17 by the sum of responses to four items assessing frequency of participation in ‘organized sports activities’, ‘school activities like clubs and bands’, ‘community activities like YMCA and scouting’ and ‘church activities like Sunday school or a church youth group’. Reliability (ICC) of this variable at these two time periods equaled +0.88 and +0.89 respectively.
