This paper examines the core features of Masahiko Aoki’s comparative institutional analysis (CIA), focusing on its methodology and institutional conceptualization. Aoki’s CIA integrates institutional and policy theory with comparative and historical analysis to explain institutional diversity and co-evolution. Departing from market-centric models, it emphasizes interdependencies among corporations, government, and society, as well as the roles of public representations and shared beliefs. Drawing on Aoki’s English and Japanese works, the paper situates CIA within his intellectual history and offers a preliminary comparison with the institutional theories of Ronald Coase, Douglass North, and Oliver Williamson. It also outlines five areas for future research, including the landscape of institutional economics, firm and corporate institutions, tech monopolies, Japan’s institutional transition and dynamic capabilities, and the co-evolution of human nature and institutions. Nearly a decade after Aoki’s passing, the paper argues that CIA remains essential for advancing institutional economics in today’s complex global landscape.