In recent decades, we have witnessed the diffusion of policy diffusion studies across many sub-disciplines of political science. Four mechanisms of policy diffusion—learning, competition, emulation and coercion—have become widely accepted as explanations for how policymaking processes and policy outcomes in one polity influence those in other polities. After pointing to major shortcomings of this inductively gained set of mechanisms, we present a theoretically more coherent typology that draws on key concepts from International Relations and Policy Studies. The four mechanisms we lay down consider rationalist and social constructivist approaches equally and they incorporate symmetric and asymmetric constellations. By further distinguishing between processes confined to one policy field and those arising from links across policy fields, we present a typology of eight theoretically consistent pathways of policy diffusion. Our framework enables the aggregation of knowledge and contributes to conceptual coherence in multi-methods research.