Differences in classroom climate and science related attitudes were investigated among junior high school science classes and students in Taiwan. The sample consisted of 1,269 students enrolled in 40 science classes distributed equally among ten junior high schools, five metropolitan and five rural. Classes were further classified according to sex (21 boys and 19 girls classes) and ability (19 high and 21 low ability classes). Using the Learning Environment Inventory (Anderson, Walberg, & Fraser, 1982) to measure climate, science classes in metropolitan schools, more than rural, were found to be characterized by Speed, Friction, Favoritism, Difficulty, Cliqueness, and Competitiveness. No differences were found in the classroom climates of classes in which students were grouped according to sex or ability. Using the Test of Science-Related Attitudes (Fraser, 1981), students in science classes in metropolitan schools, in contrast to rural, expressed more positive attitudes toward the Social Implications of Science, Adoption of Scientific Attitudes, and Attitude to Scientific Inquiry. Boys more than girls recorded high scores on Leisure Interest in Science and Career Interest in Science. High ability students were found to have higher scores on Attitude to Scientific Inquiry than did low ability students. When examining the relationship between the 15 subscale scores of the LEI and the seven subscale scores of the TOSRA for the 40 classes, only 9 out of 105 correlations proved to be significant. Most differences in climate, attitude, and their interactions were attributed to school location rather than to student characteristics.