Data were obtained from three samples of offenders: 345 offenders assessed by their probation officer specifically for the research, 278 who were actually interviewed, and 846 who were included for monitoring but were not in the assessed sample of 345. Results showed that, in the month before their arrest, 75 percent of respondents had used heroin, compared to half when interviewed after several months of supervision. Half the sample were injecting drugs during the month before arrest, and this figure dropped to 30 percent for the month before interview. Those subject to probation orders with a condition of treatment showed larger reductions in the amount spent weekly on drugs than offenders on orders without extra requirements. Those on orders with conditions appeared to be heavier drug users, with more extensive criminal histories. About 85 percent of respondents said they had been financing their drug use through crime before arrest, and one-third said they were still doing so; 90 percent of respondents said their probation officer had offered them assistance in tackling drug use, and over 50 percent felt their probation officer had helped a great deal. About 83 percent said their probation officer helped them on other issues related to drug use, such as employment and housing. Just over one-third stated the interventions that helped them most in tackling their drug use were initiated by the probation service. Policy implications of the findings for probationers who receive drug services are discussed. 2 references