Many studies have suggested that school-based professional learning communities (PLCs) should create online communities to promote teachers’ professional learning, but this topic still needs to be investigated more systematically. The purpose of this study is based on the social capital theory and visualization to analyze effectiveness in Facebook (FB) groups under two kinds of leadership styles and professional development among these teachers. Participants were the teachers of FB groups in two elementary schools in central Taiwan. Data collected for this study included posts and comments on Facebook, meeting recordings, curriculum documents, and individual interviews over a one-year period. Data were analyzed based on the theory of social capital and the concept of pedagogical content knowledge. Results indicate that the FB groups of the two kinds of leadership styles corresponded with the five key characteristics of the PLC model. In the dimension of structural social capital, network ties provided supportive conditions in both FB groups. In the dimension of relational social capital, it was possible to observe the interactions between members with a visualization diagram of energy and engagement, and PLCs of different kinds of leadership behaviors were still committed to the shared and supportive leadership in Facebook groups. In the dimension of cognitive social capital, different shared visions in the two FB groups led to different paths of intentional collective learning as well as different types of shared personal practice experiences. The implications of this study are of importance to educators and policymakers who are interested in using FB for professional development among elementary teachers.