Summary: There is a well-documented relationship between substance misuse and offending behaviour. A history of substance misuse has been identified as a strong predictor for reoffending, highlighting it as one of the foremost risk factors for criminal recidivism. Engagement with the Probation Service is a critical juncture at which assessment, intervention and appropriate referral for substance misuse issues can take place. This study aimed to identify the prevalence of substance misuse, including alcohol, among persons on probation supervision, examine the relationship between substance misuse behaviour and offending, and assess service-user engagement amongst clients on referral to the Probation Service. To achieve these aims, a cross-sectional quantitative design incorporating online survey measures was carried out with a representative sample of Probation Officers supervising people in the community. Key findings are discussed in the context of the existing research, and recommendations for Probation policy and practice are offered.