Agency theory is one the most prominent theoretical perspectives utilized in business and management research. Agency theory argues—using fundamental assumptions that agents are: (a) self-interested, (b) boundedly rational, and (c) different from principals in their goals and risk-taking preferences—that a problem occurs when one party (a principal) employs another (an agent) to make decisions and act in their stead. Essentially, the value of a principal-agent relationship is not optimized because the two contracted parties may have different interests and information is asymmetric (not equal). Agency costs are the result of principal and agent conflicts of interest and disagreements regarding actions that are taken. As such, monitoring and incentive-alignment systems are used to curb costs associated with opportunist behavior. Agency theory is commonly utilized to understand and explain corporate governance phenomena, including executive incentive alignment, board monitoring, and control of top managers; this strand of the literature is founded in economics and represents the bulk of the research in business and management. However, other important principal-agent relationships are commonly seen in business and society, such as with politicians/voters, brokers/investors, and lawyers/clients, and have benefited from the vast stream of research that has explored the principal-agent relationship in various forms and contexts. Also, alternative theoretical perspectives have emerged to accommodate variations of the principal-agent relationship. Namely, principal-principal agency, behavioral agency, and stewardship theories are prominent alternative theories that challenge, expand, or relax the basic assumptions of the classic theory to extend our understanding of important relationships and mechanisms in business and management.