Reliability of self-reports of social support with staff ratings was compared through determining the internal consistency of the measures, consistency across measures, and consistency across raters. Fifty adults with mild mental retardation and their staff in supported living residential settings were interviewed. Self-report ratings had moderate internal consistency, were consistent across rating scales, and were significantly correlated with staff ratings, although staff members tended to agree more with each other than with consumers. Results suggest that individuals with mild mental retardation can be reliable reporters about their own social support. Further, examining self-informant agreement for specific support sources can illuminate discrepancies between self- and informant-obtained ratings.