Many prostate cancer support groups (PCSGs) have formed in North America during the past decade, yet their operation or factors influencing sustainability are poorly understood. This article reports micro (intragroup), meso (intergroup), and macro (group/structure) analyses drawn from the fieldwork and participant observations conducted for an ethnographic study of PCSGs based in British Columbia, Canada. The findings indicate that effective group leadership is integral to group sustainability and the recruitment and retention of attendees. At the meso level, intergroup connections and communication were often informal; however, the primary purpose of all the PCSGs was to provide information and support to men and their families. Many PCSGs were uncertain how formal associations with cancer fund-raising societies would influence group effectiveness. Macro issues such as prostate cancer activism resided with individual group "champions" through activities coordinated by provincial and national PCSG organizations. However, activism did not guarantee group sustainability. The study findings reveal why some groups flourish while others appear untenable, and form the basis for discussion about how PCSG sustainability might be best achieved.