Why do some changes occur, and others dont? What are the factors that drive successful social and environmental movements, while others falter? How Changes Happen examines the leadership approaches, campaign strategies, and ground-level tactics employed in a range of modern social change campaigns. Some victories were achieved through full-fledged social movements, like those behind tobacco control, which entailed contentious battles between deeply divided opponents. Other changes involved sustained campaigns, like polio eradication. But whether they were driven by movements or campaigns, all major societal shifts share factors in common that separate successful efforts from the rest. How Changes Happen reveals those factors.