This mixed methods study followed an explanatory sequential design to explore the formation, development, and evolution of a formal online teacher community of practice (CoP). The online CoP supported 382 teachers as they implemented the instructional conversation (IC) pedagogy, a collaborative conversation-based pedagogy for culturally and linguistically diverse students. In the first phase, a social network analysis was conducted over 18 months to identify network attributes, patterns of engagement, node centrality measures, and evidence for homophily. This analysis served to identify two core contributors, two brokers, and two peripheral observers for in-depth interviews. In the second phase, the selected participants were interviewed to better understand their perceptions of the IC CoP and the value of their participation. In the third phase, meta-inferences were drawn based on both quantitative and qualitative findings. As a network, the IC CoP was not very dense and relied on teacher trainers to sustain engagement. As a community, the IC CoP was characterized by collaboration, mutual support, and availability of high-quality resources. Mixed evidence was found for the presence of homophily. Participants who were interviewed found personal and professional value through their participation and navigated between online and offline communities/networks. The present study reinforces the potential of online CoPs to reduce teacher isolation and foster collaboration and reflection, which may result in improved pedagogical and content knowledge. Implications about the interplay between networks and communities for teacher professional development and instructional design are discussed.