Background: Concerns about the achievement of children with asthma and respiratory conditions are especially important in New Zealand, which has one of the world’s highest rates of childhood asthma. The present study evaluated whether entering school with asthma was associated with low achievement after the first year. Methods: A child cohort was recruited to a prospective study at time of first enrollment into randomly selected schools in Christchurch. Parent interviews covered demographics and respiratory status. Physician reports were sought for children with asthma, and all respiratory information was clinically reviewed. The children’s achievement in reading and math was individually assessed at school entry and reassessed after 12 months. Schools reported absences. Intelligence subtests were administered. Results: Two hundred ninety-eight children were recruited, including 55 (18.5%) with current asthma. At 1-year follow-up, retention was 93.7%. Children who entered school with asthma were more likely to be ≥ 6 months behind other participants in reading words (P=.023) and books (P=.026), but not in math (P=.167) at the end of the first year of school. Achievement was not related to asthma severity. Entering school with asthma reliably predicted low reading achievement independent of other known covariates of low achievement (high absenteeism, minority status, male gender, single-parent family, poor academic skills at school entry, and low socioeconomic status). Conclusions: Entering school with asthma was a significant predictor of low achievement in reading at 12-month follow-up, independent of asthma severity, high absenteeism, or other covariates of low achievement.