Abstract: Interest group pluralism presumes that public policy outcomes are determined principally through a contest for influence among organized pressure groups. Most interest groups, however, do not represent themselves in this process. Rather, they rely on professional lobbyists for representation, information, and advice. These lobbyists, however, may have their own interests, which may not align perfectly with those of their clients. This Essay outlines this principal agent problem and suggests its possible implications for policy outcomes. In particular, this piece hypothesizes that the lobbyist-client agency problem may create four notable consequences: (1) it may bias policy in favor of small homogenous groups; (2) it may exacerbate status quo bias; (3) it may promote expansive delegations of power and rulemaking to administrative agencies; and (4) it may impede systematic reforms to the policymaking process.