This article presents an empirical analysis of the National Labor Relations Board, focusing on the balance the agency strikes between the interests of business and labor. It is oriented by a theoretical framework that, relative to popular models, takes a broader view of the causal structure of regulatory performance—one that simultaneously allows for presidents, congressional committees, the courts, agency staff, constituents, and economic conditions. The empirical results are instructive. All of these factors prove to have significant impacts on NLRB decisions. In addition, the core regulatory actors —Board members, staff, and constituents—are shown to engage in mutually adaptive adjustment: each is responsive to the decisions of each of the others, and their reciprocal relationships impart equilibrating properties to the system as a whole. Thus, the evidence points to a varied set of important determinants and to the dynamic nature of their interconnection. To the extent that these findings are at all characteristic of other regulatory agencies, simple popular models of regulation are likely to give anemic explanations, if not highly distorted accounts, of why agencies behave as they do.