Multi-institutional STEM reform networks have become a popular way to address the challenges facing undergraduate STEM education. Despite an intuitive sense that networks are effective reform mechanisms, few empirical research studies have investigated their impact. This qualitative case study examined the Center for the Integration of Research, Teaching, and Learning (CIRTL), a network of 38 universities that seeks to advance undergraduate STEM education through the preparation of future faculty. Using a case study design involving qualitative network maps and semi-structured interviews, this study investigated the inter- and intra-organizational boundary-spanning behaviors of key institutional representatives who link their campus to the CIRTL Network. Findings indicate that institutional representatives engaged in finding, diffusion, translation, and gaining institutional support behaviors in service to enhancing and expanding their local CIRTL programming. Results and a proposed boundary-spanning framework demonstrate the potential that such behaviors have in helping to advance post-secondary STEM education.