In this issue of JAMA Pediatrics, a large population-based Canadian study by Louis et al 1 reports that children who were born preterm do not "catch up" to their term-born school-aged peers. 1 Extending previous work in children born very preterm, 2,3 the current study found delays across all school readiness domains in children born preterm compared with those born full term, especially among those born at earlier gestational ages (GAs). At first glance, these results seem to merely confirm the findings of previous smaller studies and support what practitioners at high-risk infant follow-up clinics have asserted for years. However, the inclusion in the study of a cohort of preterm-born children with termborn siblings revealed intriguing new findings, challenging historic assumptions about follow-up models and outcomes in preterm-born infants, and suggesting new research possibilities.Louis et al 1 examined school readiness in children born preterm. 1 The outcomes of interest included all 5 domains of the Early Development Instrument (EDI), a validated and wellrounded measure of school readiness. 4 Forty-eight percent of children born at less than 28 weeks' gestation, 40% born at 28 to 33 weeks' gestation, and 34% born at 34 to 36 weeks' gestation scored as vulnerable on the EDI compared with 28% of term-born children. 1 A similar gradient was seen across GAs for children who scored as vulnerable in 3 or more domains of the EDI. 1 Other studies have also found that children born preterm were more likely than their term-born peers to have weaknesses in multiple readiness domains. 2,3 This finding may be attributed to the complexity of developmental sequences necessary to establish functional outcomes across domains. Preterm birth disrupts the entire developmental continuum, with numerous downstream implications. 5 This problem of weaknesses across domains must be addressed because the number of readiness domains affected at age 4 years is a strong factor in educational risk later, even when controlling for socioeconomic status. 3 The results of the study by Louis et al 1 challenge high-risk follow-up models that end routine developmental surveillance at age 2 to 3 years for children born preterm. 1 Although cost, time, and space constraints exist, these care models assume that someone else (family, pediatrician, or school) has the expertise and capacity to provide comprehensive surveillance for these children. Although some preterm-born preschoolers may be ready for school, other such preschoolers demonstrate deficits that may increase along with increases in developmental task difficulties. 2 Researchers have aptly described the "sleeper period" of preschool as a gap between the end of neonatal follow-up and the start of formal school assessments; it is an especially vulnerable period for preterm-born children without major impair-