Velocardiofacial syndrome (VCFS) and DiGeorge anomaly are usually associated with a microdeletion of chromosome 22q11. Clinical manifestations include conotruncal heart defects, immune dysfunction, hypocalcemia and facial dysmorphology, with a wide range of severity. Learning disabilities, mental retardation and characteristic personalities have been described as well. Our study assesses social skills, language and cognitive function in eight patients using the Social Skills Rating System, Wechsler Scales, and Clinical Evaluation of Language Fundamentals (CELF). The study population includes children ages 3 - 10 years diagnosed with chromosome 22q11 deletion by fluorescent in situ hybridization. Age and sex-matched controls were children with congenital heart disease who had similar hospital stays and numbers of surgeries compared to the patients. Tests were administered and interpreted by a psychologist who was blinded to the child's diagnosis. The subjects showed significant developmental delay with IQ scores below 81 in six of seven patients. No consistent pattern of cognitive deficits was apparent. Two of seven children tested greater than 15 points higher in verbal than performance subtests; four had no difference between verbal and nonverbal skills. Other investigators have reported higher verbal than nonverbal scores for VCFS patients. CELF measures verbal IQ by testing receptive and expressive language skills without the conceptualization and new learning required in the Wechsler. Receptive and expressive language skills were equivalent for the patients as tested by CELF. However, the average scores of the CELF for our population were approximately 10 standard points above their Wechsler scores. This difference suggests that these patients have vocabulary that they are unable to use in developmentally appropriate ways, or that they use verbal strengths to conceal a nonverbal learning disability. Our findings in VCFS subjects are similar to findings in patients with other forms organic brain injury - or psychiatric disorders.