Résumé : Introduction In 2006, the Congolese Ministry of Health developed a health system strengthening strategy focusing on health district development. This strategy called for reforming the provincial health administration in order to better support the health district development through leadership and management capacity building of district health management teams. The implementation is currently underway, yet, more evidence on how, for whom and under what conditions this capacity building works is needed. The proposed research aims to address this gap using a realist evaluation approach. Methods and analysis We will follow the cycle of the realist evaluation. First, we will elicit the initial programme theory through a scoping review (completed in December 2022, using MEDLINE, Health Systems Evidence, Wiley Online Library, Cochrane Library, Google Scholar and grey literature), a review of health policy documents (completed in March 2023), and interviews with key stakeholders (by June 2023). Second, we will empirically test the initial programme theory using a multiple-embedded case study design in two provincial health administrations and four health districts (by March 2024). Data will be collected through document reviews, in-depth interviews, non-participant observations, a questionnaire, routine data from the health information management system and a context mapping tool. We will analyse data using the Intervention-Context-Actor-Mechanism-Outcome configuration heuristic. Last, we will refine the initial programme theory based on the results of the empirical studies and develop recommendations for policymakers (by June 2024). Ethics and dissemination The Institutional Review Board of the Institute of Tropical Medicine and the Medical Ethics Committee of the University of Lubumbashi approved this study. We will also seek approvals from provincial-level and district-level health authorities before data collection in their jurisdictions. We will disseminate the study findings through the publication of articles in peer-reviewed academic journals, policy briefs for national policymakers and presentations at national and international conferences.