We studied whether children with severe developmental disabilities (SDDs) who have a comorbid behavioral disorder also have higher rates of special healthcare needs (SHCNs). We used a matched-comparison control group design to establish whether SHCNs were higher in children with SDDs with behavioral disorders versus children with SDDs without behavioral disorders. Thirty-six children were matched for age (mean 12y 6mo; range 5y 2mo-18y 8mo), sex (24 males, 12 females), ethnicity (22 non-white), mental retardation level (22 moderate, eight severe, six profound), and Diagnostic and Statistical Manual of Mental Disorders, 4th edition axis I diagnosis (18 autism spectrum disorder, 10 specified syndrome, eight mental retardation not otherwise specified). Measures included the Achenbach Child Behavior Checklist, behavioral observation, health status examination, and Childhood Health Questionnaire (CHQ). Children with SDDs with behavioral disorders had significantly higher levels of SHCN, as measured by the CHQ and health status examination. Children with SDDs with behavioral disorders had a twofold higher incidence of SHCNs than children with SDDs without behavioral disorders. No difference was observed in the number or types of prescription medication that children received. The findings suggest that SHCNs contribute to the occurrence and/or intensity of behavioral disorders in children with SDD and may require interdisciplinary care coordination.Severe developmental disabilities (SDDs) can include autism spectrum disorder, Down syndrome, and mental retardation,* among other conditions. The defining characteristics of SDDs are moderate, severe, or profound mental retardation and significant impairments in adaptive behavior that are expected to persist throughout the life-span. 1,2 Approximately 1 to 2% of children have an SDD requiring intensive, ongoing support from healthcare professionals, educators, related services professionals, and care providers. 3 Although quality-of-life outcomes can be positive for this population, such results depend on sufficient, long-term support by professionals and care providers. 4 A key moderator of quality-of-life outcomes for children with SDDs is the presence of a behavioral disorder. 5 In this population, behavioral disorders are typically expressed as self-injurious behavior, aggression toward others, and/or destruction of property. 6 Estimates of prevalence for behavioral disorders range from 14 to 17% of children with SDDs and are consistently associated with more restrictive services such as institutionalization. 7 The treatment of behavioral disorders among children with SDDs is typically environmentally-focused and related to impaired communication. 8,9 However, there is accumulating evidence from controlled experimental case studies that special healthcare needs (SHCNs) also play a role in increasing the severity and intensity of behavioral disorders in this population. [10][11][12][13] For example, sleep disorders, recurrent infections, seasonal allergies, and gastroeso...