This article, published in Public Administration Review, explores the effects of city managers' career paths on the diffusion of climate policy innovation among municipal governments in the United States. Using the agent network diffusion (AND) model, the authors hypothesize that local climate policy innovations are portable and that cities may learn from distant jurisdictions to which they are connected through the career paths of managers, a phenomenon termed the “policy wormhole” effect. Employing a dyadic panel data set of more than 400 Florida cities from 2005 to 2010, these hypotheses are tested using dyadic event history analysis. The results support both the portable innovation hypothesis and the policy wormhole hypothesis. Cities can facilitate the diffusion of policy innovations by paying special attention to the recruitment process of city managers.