This article reports on a systematic synthesis of the research methods and quality of peer reviewed empirical research relating to adult social care services (1990-2001). The range of research questions, research designs and methodological quality varied within and across four service user groups. Factors associated with variation in methodological quality included the type of research question, strategies and designs adopted, service user group, number of authors, unit of analysis and year of publication. The findings demonstrated a dearth of rigorous social care evaluations in the UK. These findings contribute to current initiatives aimed at improving the standard of health and social care research.