The purpose of this study was to examine the technical adequacy of a teacher rating scale developed expressly to measure prosocial development in young children, the Scale of Social Competence and School Adjustment (SSCSA). Using data from a sample of preschool- and kindergarten-aged children in inclusive classrooms, analyses examined the reliability and validity of the SSCSA. Results provided evidence of internal consistency and strong test-retest reliability over two weeks. Analyses of concurrent validity with criterion measures showed strong positive correlations with subscales of social skills and moderate to strong negative correlations with subscales of problem behaviors. Overall, findings provided initial evidence that supports ongoing evaluation of the technical adequacy of the SSCSA. (author abstract)