Both chronic pain and sleep problems are common for children with intellectual and developmental disabilities (IDD). Although one study has revealed a relationship between having a medical condition and sleep problems in this population, the role of pain was not examined independently. Thus, the goal of this study was to clarify the specific role of pain in children's sleep problems. Caregivers of 123 children with IDD (67 male; mean age = 10 years, 7 months (SD = 49.7 months)) completed the Children's Sleep Habits Questionnaire (CHSQ) and provided information about children's pain, function and demographic characteristics. Children were grouped as having: No Pain (86), Treated Pain (21), or Untreated Pain (16). A Multivariate Analysis of Variance (MANOVA) indicated children who had pain had significantly more sleep problems overall (F(16, 222) = 2.2, p = 0.005), and more Night Wakings (F(2, 118) = 3.1, p = 0.05), Parasomnias (F(2, 118) = 5.0, p = 0.009) and Sleep Disordered Breathing (F(2, 118) = 5.1, p = 0.008) in particular. The pattern of sleep problems varied due to whether the child was taking pain medication. Children with pain also had significantly shorter typical sleep duration (F(2, 112) = 3.5, p = 0.035). The presence of sleep problems did not vary due to functional level or whether children were taking sleep medications. However, parents of children who were taking sleep medications reported that both Bedtime Resistance (F(1, 121) = 5.7, p = 0.019) and Sleep Duration (F(1, 121) = 6.0, p = 0.016) were more problematic for them. This data indicates pain disrupts sleep in children with IDD even when it is being managed pharmacologically, suggesting pain treatment may not be effective. These results suggest that pain should be considered during evaluation and management of sleep problems in children with IDD. (Contains 4 tables.)