This symposium grew out of dissatisfaction with the existing theories of institutions. Notwithstanding significant progress in the analysis of the macro-institutions through which systemic rules and norms are established and the micro-institutions through which actors decide and implement transactions within the playing field thus defined, researchers working along one or the other dimension faced a critical and largely unanswered question: how to bridge the gap between these two institutional layers? The selected articles assembled in this issue came out of efforts to identify and understand within a unified theoretical framework the arrangements through which these layers interact. Building on contributions in economics and other social sciences as well as from in-depth empirical studies, these articles explore the relevance of the concept of ‘meso-institutions’ to designate and characterize the devices (e.g. regulatory agencies) and mechanisms (e.g. guidelines) that connect the macro- and micro-institutional layers.