This article presents a thorough analysis of dual practice among physicians who work in both the public and private sectors. A conceptual framework is presented to help the reader understand dual practice and the contexts where it takes place. The article reviews the existing theoretical and empirical literature on this form of dual practice among physicians. It analyzes the extent of this phenomenon, the underlying factors that motivate physicians to engage in dual practice, and the main implications of their decision to do so. It also examines and discusses current policies that address dual practice. In this regard, the article provides some qualified support for the use of "rewarding" policies to retain physicians in the public sectors of more developed countries, while "limiting" policies are recommended for developing countries - with the caveat that the policies should be accompanied by the strengthening of institutional and contracting environments. The article highlights the lack of quality evaluative evidence regarding the consequences of dual practice on the delivery of health care services. It concludes that the overall impact of dual practice remains an open question that warrants more attention from researchers and policy makers alike.