In the wake of the reform of the Quebec health care system in the early 1970s, thirty-two public health units (DSCs) were created. They were administratively and geographically integrated into short-term care hospitals throughout the province. This study aimed at determining (1) the influence of environmental and organizational factors on the way in which those public health units carried out their mandate; (2) the influence of these same factors on their performance in terms of level of innovation and in terms of the fulfilment of their mandate as assessed by their main clients; and (3) the influence of their activities on their performance. Our results show that the most innovative units appear to be those that have directed a large part of their efforts toward research and that have maintained close ties with other institutions and agencies. The public health units main clients differ however on their perception of the DSCs' performance.