This report reviews the research on the characteristics of youth who choose to ride with a driver who has been using drugs, alcohol or both. Understanding the demographic, psychosocial and behavioural characteristics of young passengers of impaired drivers is a key step towards developing targeted prevention programs and campaigns for those at highest risk. Although the primary focus of this review was on passengers of drug-impaired drivers, it was recognized at the outset that there would likely be substantial overlap with the characteristics of passengers of drinking drivers. Hence, it was deemed important to determine the extent of the overlap and the areas where there was a divergence of the characteristics of those who engaged in the two behaviours. This approach was taken to help decide if separate and specific prevention messages should be developed for each of the two behaviours or if they could both be served through a combined approach. The report begins with an examination of data on the prevalence of riding with a driver who has used alcohol or drugs. The characteristics of people who ride as passengers with an impaired driver are then examined in different types of studies. The report concludes with a discussion of the evidence and the implications for the development of prevention programs.