An era of financial constraints calls for effective and efficient committee work when making collective decisions. A systematic search identified research literatures in business administration, health research and service development, and social psychology addressing decision making about highly technical issues by mixed groups of people. Existing empirical and theoretical syntheses were drawn together to identify learning about the structure, processes and environment of committees and the characteristics of effective chairing. Committee performance depends upon the individuals involved, their attributes and relationships; and the time available for a committee to explore their knowledge to make choices or solve problems. In general, groups with six to twelve members tend to perform better than those in either smaller or larger groups, especially when relying on virtual communication. Diverse groups take account of a range of opinions and enhance credibility and widespread acceptance and implementation of decisions but may be more difficult to convene and manage appropriately. However, where chairs manage conflict constructively, more varied membership leads to better performance and more reliable judgements. These small-scale interactions reflect the larger scale institutional relationships, hierarchies and cultures which act as a backdrop to committee activities. These findings suggest that effective committee performance is enhanced by: appointing members from all key stakeholder groups who between them bring the appropriate range in educational and functional background, while keeping the group size close to 6-12; appointing committee chairs for their facilitation skills and generalist background rather than specialist knowledge; allowing sufficient time to allow all relevant knowledge to be shared and evaluated through discussion, especially when judgements need to be made by committees with members who vary in status; applying formal consensus development processes; and, particularly when working virtually, considering the challenges of developing trust and cohesion, and integrating divergent perspectives.