Background: Many parents with intellectual disabilities (ID) want and/or need professional guidance and support to learn skills and strategies to prevent and manage child behaviour problems. However, the available support is rarely suitable, and suitable support is rarely available. The aim of this study was to determine whether a popular mainstream parenting training programme, known as "Group Triple P" (Positive Parenting Program), could be successfully modified for this parent group. Method: A pilot study was undertaken to determine whether a modified version of Group Triple P would engage and retain parents with ID. A non-experimental, pre-test post-test study, involving a total of 30 parents with ID, was then undertaken to obtain preliminary efficacy data. Results: Parent engagement and participation levels were high. No parent "dropped out" of the programme. After completing the modified Group Triple P programme, parents reported a decrease in psychological distress, maladaptive parenting and child conduct problems. Parents reported high levels of satisfaction with the information and support they received. Conclusion: Research-informed adaptation of mainstream behavioural family interventions, such as Group Triple P, could make "suitable support" more readily available, and more engaging for parents with ID. (Contains 3 tables.)