This article reports the validity and use of a new form of the Constructivist Learning Environment Survey (CLES). As part of a larger study, a comparative student version (CLES-CS) was developed to evaluate the impact of an innovative teacher development program (based on the Integrated Science Learning Environment, ISLE, model) in school classrooms. Two separate response blocks for 30 items comprising five scales are presented in side-by-side columns to measure students’ perceptions on a five-point frequency response scale of the extent to which certain psychosocial factors are prevalent in the science class taught by a teacher who had attended the ISLE program (THIS), as well as their perceptions of other science and non-science classes taught by other teachers in the same school (OTHER). The five scales of the CLES are called Personal Relevance, Uncertainty of Science, Shared Control, Critical Voice, and Student Negotiation. Using data collected from 1079 students in 59 classes in north Texas, principal components factor analysis with varimax rotation and Kaiser normalization confirmed the a priori structure of the CLES-CS. The factor structure, internal consistency reliability, discriminant validity, and the ability to distinguish between different classes and groups were supported for the CLES-CS. Students whose science teachers had attended the ISLE program (THIS) perceived higher levels of Personal Relevance and Uncertainty of Science in their classrooms relative to the classrooms of other science and non-science teachers in the same schools (OTHER). Similar results were found when comparing the classroom environment perceptions of students whose science teachers had attended the ISLE program with the perceptions of students whose science teacher had attended alternative field trip programs (non-ISLE).