Relations between child self-reports of specific aspects of emotion regulation and specific aspects of social functioning in school were studied in two samples (N = 129/135) of 8- to 9-year-old children. The newly developed child self-report measure had significant relations to parent (Sample 1) and teacher (Sample 2) ratings of emotion regulation. In line with expectations (Rydell, Berlin, & Bohlin, 2003), poor regulation of anger and exuberance was associated with externalizing problems in both samples, poor regulation of fear had associations with social anxiety or internalizing problems in the two samples and poor regulation of sadness had marginal relations to internalizing problems in one sample. In both samples, good regulation of all emotions except fear was associated with prosocial behaviour. In Sample 1, several independent effects of child self-reports of emotion regulation on outcomes were demonstrated after controlling for parent reports of emotion regulation.