The purposes of this study were to validate an instrument of attitudes toward science and to investigate grade level, type of school, and gender differences in Taiwan's students' personality traits and attitudes toward science as well as predictors of attitudes toward science. Nine hundred and twenty‐two elementary students and 1,954 secondary students completed the School Student Questionnaire in 2008. Factor analyses, correlation analyses, ANOVAs, and regressions were used to compare the similarities and differences among male and female students in different grade levels. The findings were as follows: female students had higher interest in science and made more contributions in teams than their male counterparts across all grade levels. As students advanced through school, student scores on the personality trait scales of Conscientiousness and Openness sharply declined; students' scores on Neuroticism dramatically increased. Elementary school and academic high school students had significantly higher total scores on interest in science than those of vocational high and junior high school students. Scores on the scales measuring the traits of Agreeableness, Extraversion, and Conscientiousness were the most significant predictors of students' attitudes toward science. Implications of these findings for classroom instruction are discussed.