This guide--written for school administrators, teachers, counselors, parents, and the community--describes educational tests and measurements and test-related statistics. While specifically intended to help readers interpret the tests administered in the Los Angeles (California) Unified School District, this information may also be used to interpret other test results. Topics include: (1) why schools administer tests; (2) what tests measure; (3) objective tests and subjective tests; (4) standardized, norm-referenced, and critereon referenced achievement tests; (5) test reliability and validity; and (6) standard error of measurement. The section on scores describes raw scores, percent correct scores, percentile scores, scale scores, grade equivalent scores, stanines, and criterion referenced scores. Scores for groups (of students are also discussed: central tendency (mean, median, and mode scores) and variability (range, quartile rank and standard deviation). In the concluding section, an analysis of the real meaning of test scores is offered in which potential problems resulting from test use are cited and discussed. A 66-item glossary is appended. (GDC)