Quality education is of major public and private interest and, understandably, considerable effort is paid to the quality of schools and improvement of the level of education in society. Many governments recognize the limitations of centralized policy in motivating school improvement and turn to 'network governance' to coordinate school systems. Relying on school-to-school collaboration to coordinate education systems has far-reaching consequences for existing accountability structures, most of which were developed to support hierarchical control of individual school quality. This paper reflects on the accountability of networks of schools and on appropriate arrangements to improve the effectiveness of partnerships; our contribution starts with unpicking the question of 'who is accountable to whom and for what' in a network of schools? We discuss some common problems in the accountability of networks and describe frameworks to evaluate network-level outcomes and functioning. Examples from the accountability of Multi-Academy Trusts in England are included to contextualize our contribution.