Examining qualitative historical evidence from cases of federal regulation in the areas of labor, civil rights, and environmental policy, this article provides support for the hypothesis that divergence between legislative and executive preferences—a core and distinctive feature of the American constitutional order—creates an incentive for Congress to rely upon private lawsuits, as an alternative to administrative power, to achieve its regulatory goals. It also shows that this mechanism encouraging statutory mobilization of private litigants had been operative long before its powerful growth started in the late 1960s, that it operated in similar fashion with Republican legislators facing Democratic presidents and Democratic legislators facing Republican presidents, and that it remained a source of controversy and an active influence on congressional decision making throughout the half century covering the 1940s through the 1980s.