The Massachusetts Educational Assessment Program (MEAP) was established in 1985 to compare academic achievement among schools and districts and to give curriculum and instructional guidance. Biennially, it tests all students in grades 4, 8, and 12 in reading, mathematics, science, and social studies. Using a matrix sampling design, each student answers a small proportion of the total number of multiple-choice questions that cover all aspects of the curriculum, and a sample of students answers open-ended questions that require the application of knowledge and understanding in different contexts. When scaled scores are reported to schools, they allow comparison, but they give no information about what students can actually do. To correct this limitation, proficiency levels were developed to describe students' performance on a scale where different skills have been identified by experts as defining a given level. By implication, the description for each level defines what students at the lower levels cannot do. The proficiency levels are defined for the four subject areas at the three grade levels, and a sample question is given for each level. (SLD)