This paper reports on selected findings from an ethnographic study of drug use by young people in a Dublin inner-city community considered to be "high risk" for problem drug use. In-depth individual interviews and focus-group discussions were used to generate extensive data on the social and drug-related experiences of young people ages 15-19 years. Fifty-seven young people were interviewed individually, and a subsample of 24 took part in focus-group discussions. The paper explores young people's drug "journeys" and documents emerging drug pathways. It examines the processes relevant to young people's drug transitions, drawing attention to the role of risk perceptions and risk boundaries in decision-making about drugs. The findings highlight the role of social/contextual influences in the onward transitions to new drugs and suggest that drug choices are strongly mediated by young people's experience of, and interaction with, their social environment.