This study provides a test of a theory which suggests that student perceptions of their classroom environment affect their attitudes toward science. Using the statistical technique of cluster analysis, 27 high school science classes were divided into three distinct clusters which were most distinguishable by the amount of involvement, affiliation with students, teacher support, order and organizations, and innovative teaching strategies. One of the clusters provided a classroom environment which was significantly different from the other two and the students in that environment had more positive attitudes toward science. The dimensions of the classroom environment which make a difference are those which teachers may develop and change in order to enhance the science attitudes and, possibly, the science achievement of their students.