Background: It has been increasingly recognised that many offenders with intellectual disability (ID) have substance use issues, yet surprisingly little is known about the treatment needs of this population. Method: In order to explore pre-sentence patterns of substance use, the role of substance use in offending behaviour, and experience with substance treatment programs, interviews were conducted with 33 sentenced prisoners. Results: The findings of this study identified hazardous and harmful rates of alcohol use and high rates of substance use among prisoners with ID. Most participants reported being intoxicated at the time of their offence. Participants' experience of substance intervention programs varied. Although many reported a positive experience, others reported significant participation barriers. Conclusions: This study supports the increasingly recognised link between substance use and offending behaviour among prisoners with ID and highlights the importance of tailored and coordinated treatment initiatives, both within corrections facilities and the community.