This paper presents the main findings of the TRRL‐sponsored International Collaborative Study of the Factors Affecting Public Transport Patronage, a study which involved research workers in Australia, Canada, France, The Netherlands, New Zealand, Sweden, the United Kingdom, the U.S.A. and West Germany. The purpose of the Group's work was to assemble and review available information on the way public transport usage is affected by the many different relevant factors and to fill in some of the more obvious gaps in the knowledge by carrying out specific studies. The complete findings of the Group's work are given in The Demand for Public Transport, published by TRRL in 1980. That report is intended largely as a work of reference, but it is prefaced by an extensive ‘Executive Summary’ which forms the basis of this review.This review is presented in two parts. The first looks at the objectives of transport policy, describes past trends in patronage, costs, etc. reviews the various techniques used to predict demand, and examines the likely impacts of the main background factors such as changing affluence, car ownership and land use. The second part deals with the more direct demand factors such as fares and service levels, the impact of wider transport policies, discusses the costs of providing service and the potential for reducing them, and finally draws together both the supply and demand sides, indicating the likely implications of the findings of the study for operators, planners and policy makers.