For four decades, the World Health Organization (WHO) has helped to pioneer the development of the field of health policy and systems research (HPSR). In 1974, WHO Director-General Halfdan Mahler, recognizing the importance of research on the development of sustainable health-care delivery systems, called for an emphasis on health services and systems research. ¹ Two years later, the Advisory Committee on Medical Research, established by WHO in 1959, endorsed the definition of health services and systems research as “the systematic investigation and evaluation of specific aspects relative to the development and functioning of health services in their relationship with health related factors”. ¹ These initial efforts were important in increasing awareness of the value of HPSR and in stimulating scientific discourse about its nature and scope, as reflected by the numerous definitions and frameworks for HPSR that have followed since.