Provisions for animal rights have been included in the national constitutions of Switzerland and Germany . Protective constitutional inclusion is a major social movement success, and in view of the other movements also seeking increased political visibility and responsiveness, it is worth asking how and why nonhuman animals were allowed into this realm of political importance. This research seeks to explain how animal activists achieved this significant goal in two industrialized democracies. Using an approach drawn from the mainstream canon on (...) social movements, this comparative study attempts to show how cultural factors, institutional selectivity, and the influence of spontaneous events, along with the tactic of “frame-bridging,” determined the success of both movements. (shrink)