Our article offers an in-depth account of the role of the transnational practices of collaboration, storytelling, and learning in the diffusion of rights-based climate litigation (RBCL). Drawing on semi-structured interviews, participant observation, and quantitative data, we trace how the performance of these practices by lawyers, litigants, communities, scholars, and NGOs have fostered and sustained the transnational generation, exchange, and flow of resources, relationships, narratives, and knowledge underlying the field of RBCL. We argue that all three practices have fostered the diffusion of RBCL by influencing the local determinants of legal mobilization through enabling, discursive, and relational pathways. Finally, we show that these practices have had structural effects that have shaped the ideas and identities of the practitioners in the field of RBCL. Over time, the discursive and relational dimensions of practices have given rise to and have been strengthened by the formation of multiple communities of practice. The emergence of distinct communities provides the possibility for deeper forms of socialization and acculturation among their members, but they also make conflict and competition between different communities more likely. Overall, our article emphasizes the importance of understanding legal mobilization for climate justice as a set of practices that are shaped by the transnational social-legal context in which they are performed.