There is a growing need to design learning experiences in higher education that develop collaborative and mediated social writing practices. A wiki way of learning addresses these needs. This paper reports findings from a case study involving 58 postgraduate students who in small groups participated over eight weeks in a mediated collaborative writing project with and through wiki contexts. The project was not assessed but designed for task-based domain learning. Evaluation of the project was conducted using data drawn from multiple sources collected before, during and after the project. Findings show that participation in the project had a positive relationship with student exam performance, and web familiarity. Patterns of individual and group wiki project participation, and sex differences in participation, are discussed.