OBJECTIVES: The literature indicates that social support is protective of relapse for adolescents treated for substance use disorder (SUD). Unfortunately, no standard measure of social support exists. The objective of this research is to use factor analysis to elucidate the underlying factor structure of a 14-item social support scale for use in outcomes assessment in this treatment population. METHODS: Subjects are 517 adolescents discharged from primary substance abuse treatment from 2004-2008. The data is from research conducted between 6 and 12 months post discharge via a 234-item questionnaire that included the 14-item social support scale. The scale has questions that assess the degree to which the adolescent's social contacts conform to norms of positive behavior and therefore foster non-use and recovery. The response rate was 62 percent. RESULTS: The factorability of the scale was assessed by Keiser-Meyer-Olkin statistic (it was 0.727, > the recommended 0.6) and by Bartlett’s test of sphericity which was significant (x2=1066.89, p=0.00001). The scale was decomposed by principal component factor analysis and three factors emerged. Initial Eigen values explained 65.6, 23.1 and 11.3 percent of the variance, respectively. Final factor solutions were examined using varimax, oblimin and promax rotations with 3, 4, 5 & 6 solutions, respectively. A three-factor solution via promax explaining 99 percent of the variance emerged as the best solution although results were similar using the other rotations. Factor 1 yielded ten items that are attributes of a peers’ potential to be positive a or negative influence and thus supportive of recovery. The three items in Factor 2 related to emotional dimensions of social support. Factor 3 contained two items indicating a recovering adolescent’s ability to seek-out and establish positive social contacts. CONCLUSIONS: This scale is useful as a standard measure of social support which is an important aspect of treatment success.