In spite of all efforts to build national health services, health systems of many low-income countries are today highly pluralistic. Households use a vast range of public and private health care providers, many of whom are not controlled by national health authorities. Experts have called on Ministries of Health to re-establish themselves as stewards of the entire health system. Modern stewardship will require national and decentralized health authorities to have an overall view of their pluralistic health system, especially of the components outside the public sector. Little guidance has been provided so far on how to develop such a view. In this paper, we explore whether household surveys could be a source of information. The study builds on secondary data analysis of a household survey carried out in three health districts in rural Cambodia and of two national surveys. Cambodia is indeed an interesting case, as massive efforts by donors in favour of the public sector go hand in hand with a dominant role of the private sector in the provision of health care services. The study confirms that the health care sector in Cambodia is now highly pluralistic, and that the great majority of health seeking behaviour takes place outside the public health system. Our analysis of the survey also shows that the disaffection of the population with public health facilities varies across places, socio-economic groups and health problems. We illustrate how such knowledge could allow stewards to better identify challenges for existing or future health policies. We argue that a whole research programme on the composition of pluralistic health systems still needs to be developed. We identify some challenges and opportunities.