OBJECTIVES: To examine how and why a South-South capacity development and networking program for leadership, research, practice and advocacy on maternal new-born, child and adolescent health and health policy and systems strengthening in West Africa and Cameroon worked and identify lessons for low- and middle-income countries. DESIGN: Single qualitative case study drawing on data from document review, observations, key informant interviews and a deliberative workshop. Ethics approval for primary data collection was obtained from the Ghana Health Service Ethical Review Committee (GHS-ERC 012/10/18). SETTING: West Africa and Cameroon. PARTICIPANTS: Researchers, policy and programme managers and frontline health workers. INTERVENTIONS: Networking and capacity development. RESULTS: The programme made good progress in implementing many but not all planned capacity development and networking activities. The opportunity to network with other organisations and individuals and across countries, disciplines, and languages as well as to learn, to develop skills, and obtain mentorship support, were considered valuable benefits of the partnership. Human and financial resource constraints meant that not all planned interventions could be implemented. CONCLUSIONS: Lessons for health policy and systems research capacity building in LMIC include the potential of South-South partnerships, the need for dedicated resources, the potential of Sub-regional health organizations to support capacity building and recognition that each effort builds on preceding efforts of others, and that it is important to explore and understand where the energy and momentum for change lies. FUNDING: The work described here has been funded by IDRC Canada under research grant # 108237 "West and Central African partnership for maternal, new-born, child and adolescent health research."