Jennifer Hadden’s book achieves a rare feat for academic studies: it is expansive in its ideas and empirical investigation of them, carefully and cogently structured, and a pleasure to read. Hadden investigates the history and evolution of transnational advocacy networks in the climate change regime. She leverages natural variation—the emergence of competing networks—to investigate the inner workings of the Climate Action Network (CAN) and the more recently established climate justice network. In so doing, she develops the main argument of the book: advocacy organizations choose tactics based on their relationships.

Hadden offers a relational theory of advocacy in which “network embeddedness” is the key explanatory variable. Organizations are more likely to choose contentious forms of action if they are linked to other organizations that do the same. Similarly, more “conventional” organizations will eschew contention and use mainstream advocacy tactics when they are connected similarly conventional organizations. Birds of a feather flock together. She describes three causal effects of network embeddedness. Ties with other organizations give rise to information sharing, resource pooling, and peer pressure, all of which influence the choice of tactics. These effects are illustrated with qualitative evidence drawn from int