Why do some social movement leaders work harder than others? And, how does gender affect the patterns we uncover? Utilizing historical case study evidence of local chapters in the emerging movement opposing drinking and driving we are able to develop and test theoretical expectations about predictors of weekly effort among MADD and RID leaders. Taken together, our model explains 45 percent of the variation in leadership effort. We find bureaucratic complexity and victim support activities are more powerful predictors of effort than are individual leader characteristics, although all are important. Further analysis reveals that gender almost wholly conditions the strong effect of bureaucratic complexity on leadership effort so that increasingly complex chapter structures are associated with substantial increases in work hours for women but not men.