BACKGROUND: Despite the expanding literature on how reforms may affect health workers and which reactions they may provoke, little research has been conducted on the mechanisms of effect through which health sector reforms either promote or discourage health worker performance. This paper seeks to trace these mechanisms and examines the contextual framework of reform objectives in Uganda and Bangladesh, and health workers' responses to the changes in their working environments by taking a 'realistic evaluation' approach. METHODS: The study findings were generated by triangulating both qualitative and quantitative methods of data collection and analysis among policy technocrats, health managers and groups of health providers. Quantitative surveys were conducted with over 700 individual health workers in both Bangladesh and Uganda and supplemented with qualitative data obtained from focus group discussions and key interviews with professional cadres, health managers and key institutions involved in the design, implementation and evaluation of the reforms of interest. RESULTS: The reforms in both countries affected the workforce through various mechanisms. In Bangladesh, the effects of the unification efforts resulted in a power struggle and general mistrust between the two former workforce tracts, family planning and health. However positive effects of the reforms were felt regarding the changes in payment schemes. Ugandan findings show how the workforce responded to a strong and rapidly implemented system of decentralisation where the power of new local authorities was influenced by resource constraints and nepotism in recruitment. On the other hand, closer ties to local authorities provided the opportunity to gain insight into the operational constraints originating from higher levels that health staff were dealing with. CONCLUSION: Findings from the study suggest that a) reform planners should use the proposed dynamic responses model to help design reform objectives that encourage positive responses among health workers b) the role of context has been underestimated and it is necessary to address broader systemic problems before initiating reform processes, c) reform programs need to incorporate active implementation research systems to learn the contextual dynamics and responses as well as have inbuilt program capacity for corrective measures d) health workers are key stakeholders in any reform process and should participate at all stages and e) some effects of reforms on the health workforce operate indirectly through levels of satisfaction voiced by communities utilising the services.