Abstract: Lawyers increasingly occupy roles that cross traditional boundaries between “public” and “private.” Sometimes they do so sequentially – for example, the growing number of lawyers moving between public and private sector jobs – and sometime simultaneously – for example, the role that private practitioners play in access to justice or the practical realization of human rights norms through pro bono policies and the development of internal company rules on issues such as child labor or the environment. These developments arguably have important implications for the field of legal ethics, which tends to view a lawyer’s public and private responsibilities as either indivisible and mutually reinforcing (the traditional model), or as antagonistic and mutually exclusive (the prevailing model). In this article, I examine these implications through the lens of the growing tendency by governments at all levels to hire private lawyers to act as “substitute” attorneys general to pursue public claims against private defendants, often for monetary damages. After documenting the rise of such arrangements in cases ranging from litigation against lead paint manufacturers to the federal government’s efforts to oversee the TARP program, I discuss how this practice challenges traditional understandings of the responsibilities of both the private practitioners who assume these public responsibilities and the public lawyers who are charged with overseeing them. Contrary to the objections of some critics, I conclude that the fact that private and public responsibilities are often blurred in this context does not mean that such arrangements should be prohibited. Instead, I argue that both policymakers and lawyers should move beyond the caricatures of public and private roles that underlie many of these objections to create a new set of institutional arrangements and ethical norms that can help lawyers conceptualize and discharge their competing – and often conflicting – public and private responsibilities in particular contexts.