Since its beginnings 40 years ago, the field of learning environments has grown considerably and spread around the world. Although qualitative data-collection methods have provided important insights, a hallmark of the field today is the availability of a rich range of economical and valid questionnaires for assessing students’ perceptions of their classroom environments. As dependent variables, learning environment assessments have provided useful criteria of effectiveness for evaluating a large range of educational programs and teaching approaches. As independent variables, positive learning environments have consistently produced improved student outcomes (including achievement) for many different school subjects, grade levels and countries. Given the established links between positive learning environments and improved student outcomes, it is important that practitioners pay greater attention to assessing, monitoring and improving their classroom learning environments.