A case study was used to analyse the relationships between participation in an online discussion forum and the cognitive quality of the contributions made. Participation was calculated using two dimensions: presence (who accesses the environment, how often and for how long) and connectivity (who interacts with whom and the degree of intensity of the interaction). The discussion forum considered forms part of a course on Educational Psychology included in the curriculum of initial teacher training at the University of Barcelona and was accessed by 17 students over a period of 25 days. The analysis was carried out using a multi-method approach, which combines quantitative indicators of presence and connectivity with a content analysis of the contributions made by each participant. The results suggest that a high level of participation (high level of presence/high level of connectivity) is a necessary but not a sufficient condition for maintaining high-quality contributions throughout the discussion.