Objective: The goal of this study is to advance an approach to the assessment of the quality of studies considered for inclusion in systematic reviews of the effects of social-care interventions. Method: To achieve this objective, quality is defined in relation to the widely accepted validity typology; prominent approaches to study quality assessment are evaluated as to their adequacy. Results: Problems with these approaches are identified. Conclusion: A formal, yet explicit, multidimensional approach to assessment grounded in substantive issues relevant to the intervention and the broader context in which it is embedded is promoted. Uncritical and exclusive use of indicators of study quality such as publication status, reporting quality, and single summative quality scores are rejected. (Contains 4 tables.)