This article provides an account of the founding, growth, and success of the Inter-University Seminar on Armed Forces & Society (IUS), a long-established professional organization for those studying the military and war. How IUS has thrived invites explanation. Two theoretical themes guide our effort: first, the life cycles of organizations literature, and two, a complementary focus on the professional-career life cycles of IUS’s participants. To put together our account, we review articles about IUS’s early days and present oral history interview material from past and present leaders and members. We conclude with suggestions concerning IUS’s future directions.