This study compared the Social Skills Rating System (SSRS; Gresham & Elliott, 1990) with the revision of the SSRS, now called the Social Skills Improvement System-Rating Scales (SSIS-RS; Gresham & Elliott, 2008), across three raters (teacher, parent, and student) for elementary- and secondary-aged students. A detailed comparison of these two instruments' comparability has not been previously reported and was considered important because of the frequent use of the SSRS in many externally funded research studies and school districts across the country. Comparisons between the two instruments focused on key reliability and validity estimates across the rating scales for three raters (teacher, parent, and student) using forms for elementary- and secondary-aged students. As hypothesized, the two instruments had high internal consistency estimates and moderately high validity indices for total scores for both social skills and problem behavior scales. The reliability comparisons revealed the SSIS-RS was superior to the SSRS with regard to internal consistency estimates. The validity estimates revealed expected convergent relationships with the strongest relationships consistently found among the various common subscales across all forms of the two instruments. The authors concluded that the SSIS-RS offers researchers and practitioners assessing social behavior of children and youth a broader conceptualization of key social behaviors and psychometrically superior assessment results when using the SSIS-RS over the SSRS. Future research on the SSIS-RS is also identified and contextualized within a multitiered intervention system. (Contains 17 tables.)