The prevalence of sleep disturbance among children with developmental disabilities is known to be considerably higher than the typical population. The current study examined the effectiveness of the "Sleepwise" intervention program (O'Connell and Vannan in "Aust Occup Ther J" 55:212-214, 2008): a parent-assisted group-based treatment for sleep disturbance which was recently adapted for older children and adolescents with DD. Twenty-six families with children aged 8-17 years participated. The study compared a treatment and a wait-list control group at baseline, post-treatment and 2 months post-treatment on measures of child and parent functioning. Results demonstrated that the "Sleepwise" approach was effective in reducing sleep disturbance and parent stress. Limitations and future research directions are discussed.