WHAT'S KNOWN ON THIS SUBJECT: Previous studies that reported learning deficits among children with oral clefts mostly used small, clinic-based samples prone to ascertainment bias. No previous studies in the United States have used a populationbased sample and direct testing of academic achievement. WHAT THIS STUDY ADDS:Using a large population-based sample from the United States and standardized school tests for achievement, we found that children with oral clefts scored significantly lower than their classmates on all evaluated domains of achievement and had higher rates of learning disability. abstract BACKGROUND AND OBJECTIVE: Previous studies of academic achievement of children with oral clefts have mostly relied on small, clinicbased samples prone to ascertainment bias. In the first study in the United States to use a population-based sample with direct assessment, we evaluated the academic achievement of children with oral clefts relative to their classmates. METHODS:Children born with isolated oral clefts in Iowa from 1983 to 2003 were identified from the Iowa Registry for Congenital and Inherited Disorders and matched to unaffected classmates by gender, school/school district, and month and year of birth. Academic achievement was assessed by using standardized tests of academic progress developed by the Iowa Testing Programs. Iowa Testing Programs data were linked to birth certificates for all children. Regression models controlled for household demographic and socioeconomic factors. The analytical sample included 588 children with clefts contributing 3735 child-grade observations and 1874 classmates contributing 13 159 child-grade observations. RESULTS: Children with oral clefts had lower scores than their classmates across all domains and school levels, with a 5-percentile difference in the overall composite score. Children with clefts were approximately one-half grade level behind their classmates and had higher rates of academic underachievement and use of special education services by 8 percentage points. Group differences were slightly lower but remained large and significant after adjusting for many background characteristics.CONCLUSIONS: Children with oral clefts underperformed across all academic areas and grade levels compared with their classmates. The results support a model of early testing and intervention among affected children to identify and reduce academic deficits. Pediatrics 2014;133:785-792