The Learning Environment Inventory (LEI) measures student perceptions of the social climate of high school classrooms. The My Class Inventory (MCI), a simplified version of the LEI, is suitable for younger children 8 to 12 years of age. This manual is a revised version of a 1976 manual (previously revised in 1971). In addition to its many editorial changes, the present manual includes a comprehensive and up-to-date overview of research involving use of the LEI and MCI in numerous countries, instructions for administration and hand scoring of the two instruments, and new and expanded material related to the MCI. In particular, the version of the MCI included here is slightly different from the previous one. More comprehensive statistical information about the MCI is provided, and published research involving the MCI is reviewed. The contents of this manual include a description of the initial development of the LEI and MCI; extensive normative and validation statistics for each instrument; reviews of relevant research using these instruments; and suggestions for ways in which teachers, researchers, and curriculum evaluators might make use of the scales. Copies of the LEI and MCI, together with administration and scoring instructions, are provided in the appendices. (Author/PN)