During the course of the Transforming Naval Wargaming project for the War Gaming Department (WGD) of the U.S. Naval War College (NWC), we (CNA and the sponsor) began an extended conversation on exactly how wargames — specifically, professional military wargames — can fail. Originally focusing on the “misuse” of wargames, the conversation expanded to include all potential failure modes for professional military wargames. We called these failure modes wargame pathologies, and at some point we decided to add a brief paper on the subject to the list of deliverables. The goal of this paper is to discuss some of the issues involved in the diagnosis and prevention of such pathologies as part of a continuing effort to advance the state of the art of wargame design.