Data were collected from interviews with 234 prisoners from four Scottish adult male prisons. Following a description of the participants' security status, prison career, personal details, and drug using characteristics, the report discusses in detail the prisoners' past drug use, imprisonment as a factor in introducing people to drug use, participants' regular drug use in the community, and their drug use during current sentence. The next chapter discusses the practice of sharing drug-injecting equipment within prison. Results of reliability studies are presented. Another chapter provides case study data of HIV-positive prisoners. The remainder of the report discusses service provisions for drug users in the Scottish prison system, the prison staff perspective, and the objective data collected from prison records. 1 appendix