Background: The Equipping Youth to Help One Another Programme (EQUIP) was designed for young offenders to address a developmental delay in moral reasoning, distorted cognitions and social skills. Methods: The present authors undertook a single case series study and piloted an adapted version of the EQUIP programme with three men with intellectual disabilities and four men with a diagnosis of Asperger Syndrome, all of whom were detained in a medium-secure forensic unit for people with intellectual disabilities. Treatment was delivered over a 12-week period, and participants took part in four-one-hour sessions per week. Results: The results suggested that treatment was successful at increasing moral reasoning ability, reducing distorted cognitions and improving ability to choose effective solutions to problems. However, treatment did not have a significant effect upon anger. Conclusions: The EQUIP programme is a promising treatment, but further research is needed to investigate its effectiveness with men with intellectual or other developmental disabilities. (Contains 7 tables and 1 figure.)