While movement activists spend much of their time and energy trying to change the world and we think that social movements often matter, our theoretical and empirical knowledge in this field is still relatively poor. Social Protest and Policy Change offers a systematic and empirically grounded analysis of the impact of three major contemporary movements on public policy. Following a comparative and historical perspective, the author argues that the policy impact of social movements is facilitated by the presence of favorable political opportunity structures, and more precisely by the presence of institutional allies among the elites, and by a favorable public opinion. Furthermore, the very content of the movements' demands also plays a role, insofar as the power holders are more willing to make concessions on certain issues than on others. On the basis of a historical overview of the mobilization of ecology, antinuclear, and peace movements in the United States, Italy, and Switzerland, and using a unique body of original data, the book presents the results of time-series analyses showing the joint effect of protest, political alliances, and shifts in public opinion for movements that do not address issues that pose too serious a threat to the power holders.