Various factors and tactics are more likely to help protest movements achieve their goals, than other factors. This resource summarizes and characterizes existing research on movement success and failure. Nonviolent tactics and large numbers of movement participants as factors that lead to success are shown by a large body of evidence. There is some evidence—but weaker—that a diverse range of movement participants and a nonviolent “radical” flank help protest movements succeed. There is very little evidence that committed protestors who regularly attend protests leads to success. This report details these and other factors further.