To assess the longitudinal development of intelligence and its relation to school performance in a nationwide cohort of neonatal extracorporeal membrane oxygenation (ECMO) survivors and evaluate predictors of outcome at 8 years of age. Repeated measurements assessed intelligence of neonatal ECMO survivors at 2, 5, and 8 years (n = 178) with the use of validated, standardized instruments. Selective attention (n = 148) and type of education were evaluated in the 8-year-olds. Intelligence remained stable and average across development (mean ± SD IQ: at 2 years, 102 ± 18; at 5 years, 100 ± 17; and at 8 years, 99 ± 17 P = .15). Children attending regular education without the need for help (n = 101; mean z score: -1.50 ± 1.93) performed significantly better on the selective attention task compared with those children who needed extra help (n = 65; mean z score: -2.54 ± 3.18) or those attending special education (n = 13; mean z score: -4.14 ± 3.63) (P = .03). However, only children attending special education had below-average intelligence (mean IQ: 76 ± 15), compared with average intelligence for those attending regular education, both with help (mean IQ: 95 ± 15) and without help (mean IQ: 105 ± 16). Compared with children with other diagnoses, children with congenital diaphragmatic hernia (CDH) scored significantly lower on both IQ (CDH, mean IQ: 93 ± 20; meconium aspiration syndrome, mean IQ: 100 ± 15; other diagnoses, mean IQ: 100 ± 19 P = .04) and selective attention (CDH, mean z score: -3.48 ± 3.46; meconium aspiration syndrome, mean z score: -1.60 ± 2.13; other diagnoses, mean z score: -1.65 ± 2.39 P = .002). For the majority of neonatal ECMO survivors, intelligence testing alone did not identify those at risk for academic problems. We propose internationally standardized follow-up protocols that focus on long-term, problem-oriented neuropsychological assessment.