Intermunicipal cooperation is being increasingly adopted in various countries to cope with the dilemmas of territorial scale and resource rationing. Despite the pressures towards the reshaping of administrative boundaries, little is known about the capacity of intermunicipal associations to function as effective, legitimate and resilient policy actors. This article aims to contribute to this debate by addressing two interrelated dimensions. First, it seeks to present a conceptual definition of governance capacity, unpacking the conceptual framework into dimensions that can be measured systematically. Second, it aims to empirically assess the governance capacity of Portuguese intermunicipal associations, drawing on a unique survey of intermunicipal associations. Overall, results suggest that despite being instrumentally driven, intermunicipal associations have proven to be efficient, with members recognizing the benefits and the spillover effects of trustworthy arrangements. However, the path dependencies affecting Portuguese local governments may impact on the relatively low levels of governance capacity. Points for practitioners This article undertakes a conceptual analysis of the governance capacity of intermunicipal associations. This analytical framework can be crucial for leaders, practitioners and professionals working in management and administration especially those working in complex and demanding settings. Given the general trend towards intermunicipal cooperation – strongly encouraged by national and European regulations and reforms – practitioners need to be able to measure the capacity of the cooperative arrangements to be established and to be maintained. This article also strives to enlighten those professionals as to which dimensions mostly need to be strengthened so as to allow intelligent collective choices to be made and to set strategic directions for the allocation of (increasingly) scarce resources.