Over the past few decades, research on policy adoption and diffusion has grown rapidly. Despite the relatively large number of publications, however, little attention has been paid to the important question of why a policy is differently implemented or diffused across governments. To answer this question and improve our understanding of local policy choice beyond widely cited neighboring influences, we closely examine the roles of three main policy actors—internal actors, external actors, and go-betweens—in the local policy diffusion process, drawing particularly upon property tax reassessment scenarios. In addition, we focus on nested institutional arrangements, including form of government and type of property tax assessor, that affect th...