OBJECTIVE: To estimate the association between small for gestational age (SGA) at birth and educational performance on standardized testing and disability prevalence in elementary and middle school. STUDY DESIGN: Through linked birth certificates and school records, surviving infants born at 23-41 weeks of gestation who entered Florida's public schools 1998-2009 were identified. Twenty-three SGA definitions (3rd-25th percentile) were derived. Outcomes were scores on Florida Comprehensive Assessment Test (FCAT) and students' disability classification in grades 3 through 8. A "sibling cohort" subsample included families with at least 2 siblings from the same mother in the study period. Multivariable models estimated independent relationships between SGA and outcomes. RESULTS: Birth certificates for 80.2% of singleton infants were matched to Florida public school records (N = 1 254 390). Unadjusted mean FCAT scores were 0.236 SD lower among <10th percentile SGA infants compared with non-SGA infants; this difference declined to -0.086 SD after adjusting for maternal and infant characteristics. When siblings discordant in SGA status were compared within individual families, the association declined to -0.056 SD. For SGA <10th percentile infants, the observed prevalence of school-age disability was 15.0%, 7.7%, and 6.3% for unadjusted, demographics-adjusted, and sibling analyses, respectively. No inflection or discontinuity was detected across SGA definitions from 3rd to 25th percentile in either outcome, and the associations were qualitatively similar. CONCLUSIONS: The associations between SGA birth and students' standardized test scores and well-being were quantitatively small but persisted through elementary and middle school. The observed deficits were largely mitigated by demographic and familial factors.