Fostering a strong sense of community among students within online courses is essential to supporting their learning experience. However, there is little consensus about how different facilitation methods influence students' sense of community or behaviors. This lack of understanding means instructors do not have the information they need to select an appropriate facilitation method when teaching online. This challenge is further complicated by a poor sense of how community building is influenced by the length of an online course. To better understand the relationship between these factors, we explored students' sense of community across four graduate-level online courses. Two of these courses employed an instructor-led form of facilitation and two employed a peer-led form of facilitation. For each facilitation method, one course lasted an entire term (12 weeks) and the other lasted half a term (6 weeks). This two-by-two betweensubjects design is augmented with interview data. This design enabled the study of both variables and possible interaction effects. The findings revealed students in instructor-facilitated courses experienced a stronger sense of community. Longer courses were also associated with a stronger sense of community, although the relationship was weaker than that of facilitation. No interaction effects were detected between facilitation method and course length. Follow-up analyses examined the relationship between facilitation style, course length, and a set of twelve student behaviors (e.g., note writing, note reading, and replying). The results revealed that both facilitation style and course length were associated with differences in students' note attributes including note length, the Flesch-Kincaid grade level of the text, and the frequency of their replies. Collectively, these findings offer evidence that both facilitation style and course length are related to students' sense of community and the behaviors they exhibit online.