Pre-print, Working paper: Many decisions in private and public organizations are made by groups. The paper explores strategies that the sponsor of a proposal may employ to convince a qualified majority of group members to approve the proposal. Adopting a mechanism design approach to communication, it emphasizes the need to distill information selectively to key members of the group and to engineer persuasion cascades in which members who are brought on board sway the opinion of others. The paper unveils the factors, such as the extent of congruence among group members and between them and the sponsor, and the size and governance of the group, that condition the sponsor's ability to maneuver and get his project approved.