How do we explain the paradox that Bangladesh has made remarkable progress in health and human development, yet its achievements have taken place within a health system that is frequently characterised as weak, in terms of inadequate physical and human infrastructure and logistics, and low performing? We argue that the development of a highly pluralistic health system environment, defined by the participation of a multiplicity of different stakeholders and agents and by ad hoc, diffused forms of management has contributed to these outcomes by creating conditions for rapid change.