Pi Gamma Mu or ΠΓΜ is the oldest and preeminent honor society in the social sciences. It is also the only interdisciplinary social science honor society. It serves the various social science disciplines which seek to understand and explain human behavior and social relationships as well as their concomitant problems and issues. Pi Gamma Mu's constitution defines the social sciences to include the disciplines of history, political science, sociology, anthropology, economics, psychology, international relations, criminal justice, social work, social philosophy, history of education, and human geography. Membership is also extended to interdisciplinary social science fields that build on the core social science disciplines, such as business administration, education, cultural and area studies, public administration, and organizational behavior.

In the United States, an honor society is an organization that recognizes individuals who excel in various domains such as academics, leadership, and other personal achievements, not all of which are based on ranking systems. These societies acknowledge excellence among peers in diverse fields and circumstances. The Order of the Arrow, for example, is the National Honor Society of the Boy Scouts of America. While the term commonly refers to scholastic honor societies, which primarily acknowledge students who excel academically or as leaders among their peers, it also applies to other types of societies.