Résumé : A dominant theoretical narrative has emerged in the substantial body of professional development literature that uses the social network perspective, under the too-simplistic justification that “relationships matter”. This overarching narrative tends to obscure the diverse perspectives and nuances within the literature regarding the theoretical rationale for the connection between the social network perspective and teacher professional development (TPD). The primary aim of this systematic review is to highlight and reflect upon the various theoretical rationales linking the social network perspective and TPD, as seen in the relevant empirical research. From 1475 records identified in Scopus, Psycinfo, and Eric, we retained 51 articles after screening titles and abstracts, followed by full-text screenings. We used a combination of deductive and inductive approaches to analyze our final set of 51 studies. Our results present an integrated conceptual model with four distinct rationales for connecting the social network perspective and TPD: (1) the network as a source of professional development, (2) the network as a catalyst for enactment and sustainability of reforms with TPD, (3) the network as purposefully (re)shaped by professional development initiatives, and (4) the network as a (latent) school capacity for teacher and school development. In the discussion, we particularly reflect on these rationales along two key dimensions: the functional role of the network (independent vs. dependent variable) and the ontological stance toward the network (active vs. passive).