Purpose: This article explores two intermediary organizations that are attempting to alter the landscape of US education by building organizational networks and professional capital that disrupt traditional relationships between K-12 education and higher education. Design/methodology/approach: The work is a theory-driven, comparative case study of the University Council for Educational Administration (UCEA) and the National Network of Education Research-Practice Partnerships (NNERPP). Through the lens of institutional theory, the authors employ an extended case method that uses comparative analysis of situationally-embedded organizational case studies to build theory. Findings: The two organizations play an intermediary role by The two organizations play an intermediary role by establishing new standards, norms, and patterns of practice between higher education and local systems of education. In doing so, these organizations serve as meso-institutions, alliances that mediate the processes of institutionalization and play essential parts in developing new facets of infrastructure and new professional identities that hold the potential for nurturing and sustaining professional capital. System leadership hinges on strategic bricolage to identify near-term next steps that align with longer-term strategic goals related to field building. Originality/value: Professional capital as a concept was initially characterized from a bottom-up perspective, valorizing the agentive dimensions of human, social and decisional capital in opposition to top-down, centralized control. Our conceptualization of intermediary organizations as meso-institutions addresses how the processes of mediated networking and system leadership operate to build professional capital in specific ways that crystallize institutional change.