Improvement networks are a novel organizational form designed to support collaborative, interorganizational learning and improvement aimed at solving complex, interdependent problems spanning classrooms, schools, systems, and their broader contexts. These networks aim to develop and augment local capabilities for innovation and improvement by creating an organizational structure to coordinate educator driven inquiry that explores the impact of practice changes and the adaptations that support the spread of promising practices across contexts. This article introduces a framework grounded in the Networked Improvement Community (NIC) concept that describes the social and cultural components of a high-functioning improvement network: the Improvement Network Health and Development framework. This framework was developed and iteratively refined through a review of literature and theory on networked improvement in education and other sectors, as well as the authors' practice-based knowledge generated through deep engagement in the operation and developmental evaluation of multiple NICs. The framework describes six critical domains of activity--hub leadership; structuring network roles and engagement; continuous improvement processes; connections within improvement teams; connections across improvement teams; and network culture--and how improvement networks are embedded in complex institutional environments. The framework was developed to be an analytic tool for network leaders, evaluators, and researchers to think and reason about healthy improvement networks. In this sense, it is both a practical framework and a theory of the way NICs operate as scientific-professional learning communities.