This longitudinal study evaluated the amount and type of interaction and interpersonal content in messages posted by online graduate students in small group asynchronous forums. It also assessed the relationship between interpersonality and interactivity. To achieve this, a new coding scheme was developed to categorize the content of online forums. The results suggest that cultivating interpersonality online leads to increased participation and expands the depth of discussion, thus facilitating online collective knowledge building. Finally, regulating the complexity of interactions and fostering the development of a cohesive group of participants through increased interpersonal exchanges may render more controlled patterns of interactive online behavior and improve collective learning.