In this article we examine the emergence and implications of transnational climate- change governance. We argue that although the study of transnational relations has recently been renewed alongside a burgeoning interest in issues of global governance, the nature of transnational governance has to date received less attention. We contend that transnational governance occurs when networks operating in the transnational political sphere authoritatively steer constituents toward public goals. In order to stimulate a more systematic study of the diversity and significance of this phenomenon, the article develops a typology based on the actors involved and their authority—public, private, or hybrid—and the primary governance functions performed in order to steer network constituents— information-sharing, capacity building and implementation, or rule-setting. A comparative discussion of transnational governance networks for climate change illustrates each category and the value of the typology in assessing the multiple mechanisms through which transnational governance occurs. In conclusion, we suggest that our typology provides a useful starting point for future research and reflect on the implications for the study of global affairs.