Data from the 1983–84 Israeli IEA (International Association for the Evaluation of Education Achievement) science study were used to explore gender-related differences (and their determinants) in the learning of science. The sample was composed of 1,934 ninth-grade students. The study involved several measures of science learning, ten attitudinal measures, and items and errors classification. Differences between boys and girls were observed in some measures of science performance–-particularly in the physical sciences, in items with lower estimates of “opportunity to learn,” and in specific kinds of errors. Gender-related differences were also observed in the predictive model of achievement, using science-specific affective measures. The discussion raises the cognitive and affective readiness of boys and girls for learning science.