Data collected from 937 parent questionnaires regarding intelligibility of speech in children with Down syndrome were analyzed. Intelligibility was a wide-spread problem. Parents reported evidence of difficulties classified as oral motor skills, motor programming skills, and specific speech skills. Children experienced greater difficulty with sentences and in conversation than with single words. Intelligibility problems were more frequent when the child was conversing with unfamiliar adults. The implications of these findings for clinical assessment and remediation are discussed.