This paper focuses on evaluating a socio-cultural activity design (SCAD) model for using discussion-based social networking tools as a means to support the development of an online community of learners. Participants included 38 undergraduate students enrolled in a human-centered design course at a large, US university. The SCAD model includes concrete markers for identifying expected interactional, communication patterns for a community of learners. In order to examine the utility of our model we asked, (RQ1) to what extent do social network patterns coincide with expected outcomes for a community of learners; (RQ2) To what extent do students' cognitive activities in the environment match expected outcomes for a community of learners. To answer these questions, we conducted social network and content analysis of 503 posts in an online discussion-based social networking tool. We examined the overall sophistication of posts as well as changes in posting behavior over time. Findings suggest that use of the SCAD model facilitated processes associated with a community of learners, as students took over responsibility for the discussions over time, maintained strong connections with multiple peers, engaged in meaningful conversations about course content, and increased the sophistication of cognitive activity over time, even after instructor faded from the environment. However, findings also suggest more support is needed for online argumentation practices.