Despite international interest in research on classroom environment, very little attention has been given to exploring how mathematics teachers might apply ideas from that research in guiding practical improvements in mathematics classrooms. To facilitate the use of classroom climate assessments, an economical, hand-scorable short form (25 items) of the My Class Inventory was developed. Data supported each scale's internal consistency, discriminant validity, and ability to differentiate between the perceptions of students in different classrooms. Some methods for improving classrooms are illustrated in a case study of a successful change attempt in a sixth-grade mathematics class. When assessments of actual and preferred environment were used in an attempt to improve the climate of the class, a significant improvement occurred only on the dimension on which change had been attempted.