Parental mental illness can have long-lasting impacts on a child's life. Although programs exist in supporting the needs of young children, there remains a paucity in programs that address the needs of adult children. A two-round Delphi study with adult children, academics and clinicians who have experience with parental mental illness was employed. A total of 45 and 24 participants participated in rounds one and two respectively. Open-ended questions in round one around program design and content were thematically analysed, and subsequently rated in round two. Adult children specifically identified four topics of need: (i) managing multiple roles, (ii) emotional regulation, (iii) setting relational boundaries and (iv) transition to parenthood. Current results provide the foundation for the development of modular programs that could be pilot tested with adult children who grew up with parents with mental illness.