This is a reference tool that provides information on the organization and composition of transit boards. The Guidebook describes the structure and practices of transit boards and includes information on board-selection methods, board size, board length of service, and board composition. The Guidebook also includes a section on the primary role and activities of the transit board and the role of the transit board chair. There are guidelines for determining the roles and responsibilities of board members and a description of the characteristics of an effective board. The Guidebook may be used by policymakers, general managers, legal advisors, and board support personnel. The companion document to the Guidebook is a report, Public Transit System Policy Boards, that focuses on the findings of the research. A literature review was completed to identify characteristics of governance boards in the public transit industry. A national survey was conducted to identify the characteristics and effectiveness of public transit boards. Five focus groups and six case studies were conducted to discuss transit board effectiveness and the operation of transit boards. This report is published as TCRP Web Document 21, available at: www4.trb.org/trb/crp.nsf.