This dissertation studies the history, contemporary network, and impact of the animal rights movement in Europe—a region that is often regarded as particularly progressive in matters of animal welfare. Each chapter connects to important debates in social movement studies. The first chapter analyzes the origins of animal advocacy in the 19th century by ‘bringing political economy in’. Such a perspective provides important insights for understanding a case of activism that has been typically regarded as primarily driven by ‘morals.’ In the second chapter I explore the network of the contemporary animal rights movement. Using an innovative methodological approach, I collect relational data on ‘SMO populations’ and trace the patterns of connections between more than 1500 organizations and groups. The remaining chapters focus on the impact of the movement. The third chapter studies the most public recent instance of animal rights activism in Europe: The Stop Vivisection European Citizens’ Initiative (ECI) against animal experimentation. It shows how the ‘opportunity structure’ of the ECI benefits activists of populous member states instead of incentivizing Europe-wide campaigns. I also discuss the multiple consequences of Stop Vivisection beyond the failure to achieve policy change. The fourth chapter studies a largely non-public approach in the political conflict over animal experimentation: the push for the development of ‘alternatives,’ underling that new technologies are a neglected, and contested, outcome of activism. The fifth chapter analyzes the limited gains of activists in the regulation of egg production and animal experimentation more generally. Despite widespread praise for two major EU directives, this chapter argues that gains for animals have remained modest—and that issue-specific contextual factors matter for future developments. Overall, while the actions of the vibrant animal rights movement in Europe have produced a variety of consequences, gains for animals have so far been limited.