INTRODUCTION AND AIMS: Few epidemiological studies have examined the behaviours and experiences of young adults during discrete drug-use events. This study was designed to capture a rich, detailed description of discrete occasions or 'sessions' of psychostimulant use. DESIGN AND METHODS: Participants were 220 young psychostimulant users living in Melbourne, Australia, recruited through targeted advertising in entertainment street press, on websites, at events/dance parties and through peer referral between September 2007 and March 2008. The research identified the timing, sequence, frequencies, quantities and modes of alcohol and other drug administration during the participants' most recent session of psychostimulant use and explored the contexts and settings in which drug use took place. RESULTS: Participants were well-educated young people who used a variety of different drugs. Their most recent session of psychostimulant use was reported as highly enjoyable and typical of their other sessions of psychostimulant use. The session lasted a median of 20 h, and in most cases, simultaneous drug use was the norm, and large quantities of alcohol, psychostimulants and other drugs were consumed. Acquisition of illicit drugs commonly occurred through social networks during the course of the session and significant sums of money were reportedly spent. DISCUSSION AND CONCLUSIONS: Findings point to a range of priorities for future research and public health interventions aimed at young psychostimulant users, focused primarily on reducing the prevalence and consequences of simultaneous and heavy/binge drug use.