This paper reports the partitioning of variance in scale scores from the use of three classroom environment instruments. Data sets from the administration of the What Is Happening In this Class (WIHIC) to 4,146 students, the Questionnaire on Teacher Interaction (QTI) to 2,167 students and the Catholic School Classroom Environment Questionnaire (CSCEQ) to 2,211 students in Australian schools were analysed using MLwiN. Variance components models with three levels (viz. student, class and school) for each of the 22 scales were created. Results revealed that statistically significant proportions of variance in all scale scores could be attributed to the student and class levels. Apart from one scale, no school level variance in scale scores was statistically significant. Typically, variance proportions were above 75% at the student level, above 15% at the class level, and below 5% at the school level. Multilevel analyses should be conducted with classroom environment data. (Contains 3 tables.)