This paper presents the findings of a multi-centre study assessing the impact of Health Workers for Change (HWFC) workshops in seven different primary care sites, based on the common core protocol described in this paper. The paper discusses a common methodology used by the studies, consisting of a triangulation of qualitative and quantitative methods. Such methodologies are inherently complex as they require comparisons across systems, sites and procedures. The studies were conducted in six sites in Africa and one site in Argentina. Generally, the intervention resulted either in positive change or in no change, except in the area of staff relationships where conflicts were more frequent after the intervention than before. This may reflect a willingness to confront problems or contentious issues. Implementing the HWFC workshops improved provider-client relations, facility level functioning and aspects of staff interrelationships, and had some impact at the system level. All studies indicated that overall health system development is essential for improved service provision including quality of care. The findings also indicated that this intervention complemented and could assist health sector reform efforts and can play a role in sensitizing health workers to gender issues. The paper concludes with a discussion of the robustness of the methodology used in the studies.