This study evaluated the online participation of 40 students who, while studying a graduate programme in a fully online higher education institution, were assigned to small online groups for a four-week period in order to develop a written task. The type and frequency of their postings in the online forums were analysed. In addition, knowledge outcomes were evaluated and correlation analyses were applied to identify relationships between frequency and types of online postings and knowledge acquisition. Findings show a correlation between content-oriented postings and individual knowledge acquisition. There was also significant correlation between new ideas and critical evaluation postings, with all types of knowledge evaluated at an individual level. The results suggest that instructors should be concerned with types and frequency of messages students post in online small groups in order to stimulate active participation and high-cognitive quality postings.