Data from 1,467 high school students in New South Wales schools on the Individualized Classroom Environment Questionnaire (ICEQ) were analyzed using multilevel variance components models to derive intraclass correlat ons to determine the degree to which ICEQ scores may validly be said to measure aspects of classroom climate as against individual student attitude. The results showed that the class variable accounted for large and noteworthy proportions of overall variance in all five ICEQ scales. Subsequent analyses showed that only small and nonsignificant proportions of variance were attributable to the school variable. In these terms, the ICEQ may be considered to be a relatively good measure of classroom climate. Copyright © 1999 Sage Publications, Inc.