This paper investigates the effects of group support systems (GSS) and content facilitation on individual knowledge acquisition in general, and on changes in an individual's knowledge structures in particular as indicated through concept mapping development. We present a model explaining the enabling effects of GSS and content facilitation on group processes (group participation, quality of feedback, domination, and communication barrier), cooperation in learning, and individual knowledge ledge structures (knowledge complexity, integration, and commonality). An experiment that employed a 2×2 factorial design was used to explore the main and interaction effects of GSS and content facilitation on knowledge acquisition. Experimental subjects were randomly assigned to one of the four treatment groups; that is, nonfacilitation and non-GSS, nonfacilitation and GSS, facilitation and non-GSS, facilitation and GSS. Results of the experiment indicated that both GSS and content facilitation positively affect certain aspects of individual knowledge acquisition. Content facilitation particularly enhanced learners' knowledge commonality, whereas GSS enhanced the quality of feedback and cooperation in learning, and reduced domination and communication barrier. However, the results also indicated that GSS and content facilitation have crossover interaction effects on group participation and knowledge commonality. The effects of combining GSS and content facilitation were not additive in this study. Explanations are presented.