This study involved the development of separate personal and class forms of a new classroom environment instrument which synthesises salient dimensions from existing instruments as well as including relevant new dimensions. Personal forms are more appropriate for identifying differences between subgroups of students within a class and in the construction of case studies of individuals. Quantitative methods and qualitative methods were combined both in the validation phase and in several research applications. Following a pilot study, the questionnaire was administered to a sample of approximately 800 high school science students in 30 science classes. The study resulted in a new widely-applicable classroom environment questionnaire with similar statistical characteristics for the personal and class forms. It was found that: student perceptions on the `personal' form were systematically less positive than their perceptions of the same class using the conventional `class' form; gender differences in classroom environmen= perceptions were greater for the `personal' fonn than for the `class' fonn; and attitude-environment assoc=ations were of comparable magnitudes for the `personal' and `class' forins, although each fonn accounted for unique variance in attitude scores.