This chapter provides a systematic comparative analysis of Track 1.5 Diplomacy as practiced by the United States and European actors, establishing two fundamentally divergent yet globally influential models. The US model is rooted in pluralism and neoliberalism, characterized by a decentralized, bottom-up structure where non-state actors (diaspora lobbies, think tanks, corporations) operate with high financial and functional autonomy. This pragmatic, results-oriented approach thrives on dynamism and responsiveness but risks policy fragmentation and inconsistency. Conversely, the European model, exemplified by the EU and Norway, is anchored in normative power theory and social constructivism, prioritizing a centralized, top-down integration of non-state actors into formal structures (EEAS, structured dialogue) to promote universal values, strategic coherence, and long-term peacebuilding. The European approach demonstrates greater institutional stability but can suffer from bureaucratic inertia. The comparison across operational, institutional, and financial dimensions underscores that the effectiveness of each model is highly contingent on its political culture. Finally, a contrasting analysis with the ASEAN model, characterized by its adherence to the “ASEAN Way” of non-interference and consensus-building, highlights the cultural contingency of Track 1.5 practices. This comprehensive comparison affirms that while the tools of hybrid diplomacy are universal, their successful application requires tailored alignment with regional governance logics and strategic objectives.