Studies of policy diffusion – examining how and why similar policies spread across different polities – tend to treat policymaking institutions as unitary actors. The information obtained from observing other countries’ experiences, the policy decision-making process, and the implementation of policy choices are traditionally seen to be contained within a single, abstract ‘policymaker’. This thesis challenges this view by advancing an organizational perspective on policy diffusion. It develops a theory that attributes information processing, decision-making, and policy implementation to three different within-polity agents – ’learning’ bureaucrats, policy decision-makers, and ‘executing’ bureaucrats – whose interactions are mitigated by bureaucratic and organizational variables. Based on this framework, I develop a formal model of diffusion likelihood and derive three hypotheses. I evaluate these hypotheses in the context of the diffusion of open trade regimes among developing countries between 1970-2000. Empirical results suggest that bureaucratic interactions may explain previously unexplored patterns in the diffusion of trade policies. Overall, this theoretical framework may offer insights into the organizational elements that underlie other processes studied in comparative international political economy.