The purpose of this article is to describe the development, validation and use of the "Constructivist Multimedia Learning Environment Survey" (CMLES). This questionnaire assesses teachers' and students' perceptions of the learning environment when students use online multimedia programs while teachers use constructivism as a referent for their teaching. The design of the questionnaire was based on a constructivist approach to learning and focused on the process of learning with the multimedia program and on the nature of that program. Before the use of the CMLES becomes widespread, it was important to determine whether it is valid and reliable. Therefore, a study involving 221 students in 12 high school classrooms into statistical validation and interpretive validation of the questionnaire was undertaken. For this sample of Grade 10 and 11 students who completed the actual and preferred forms of the questionnaire, the CMLES scales demonstrated a high degree of internal consistency reliability (with alpha reliability coefficients ranging from .73 to .82), as well as satisfactory factorial validity and discriminant validity. Therefore, the study supports the reliability and validity of the CMLES for assessing students' and teachers' perceptions of one important aspect in evaluating learning environments which promote the use of multimedia programs and constructivist learning approaches.