Facilitation in GSS meetings is considered among the most important critical success factors for effective GSS application. A considerable amount of research on GSS facilitation has been carried out, yet this research has been biased by a facilitator's perspective. In this study, we investigated participants' perceptions of effective GSS facilitation. Based on transcripts of interviews with participants, we produced a comprehensive overview of tasks and behavior that participants felt were crucial for the effective facilitation of GSS meetings. Comparison and contrast with existing facilitation task taxonomies showed that our results complement existing insights and add further detail to it.