Parents' understanding/expectations regarding genetic testing for children with developmental disorders were explored. Within a month of testing, interviews were conducted with 57 parents. Many (74%) could not recall the nature of testing. Parents expected genetic testing to have positive impacts for the child (93%) and the family (98%), mainly to find the etiology and/or an intervention. Many parents (40%) reported not knowing their child's clinical diagnosis. They expected genetic testing would establish the diagnosis. Parents anticipated potential negative impacts of testing for children (78%) and families (87%), mainly finding another illness or not finding potential interventions. Abnormal results explaining the disorder were found in 9% of children. In summary, genetic results for developmental disorders are unlikely to meet parental expectations.