Children completed a 13-item scale composed of items such as “I try to help others,” which was adapted from Pastorelli, Barbaranelli, Cermak, Rozsa, and Caprara (1997). Items were rated as 1 = never, 2 = sometimes, or 3 = often. A single scale was computed as the average of the 9 prosocial behavior items (the remaining 4 items were distracters). The child self-report version of the prosocial behavior scale is significantly related to peer- and mother-rated prosocial behavior, indicating reporter validity.
Pastorelli, C., Barbaranelli, C., Cermak, I., Rozsa, S., & Caprara, G. V. (1997). Measuring emotional instability, prosocial behavior and aggression in pre-adolescents: A cross-national study. Personality and Individual Differences, 23, 691-703