Two types of diagnostic reading tests are described--tests of phonics skills and tests of work-study or critical reading ability. The following criteria for evaluating these tests are suggested: (1) an analysis of the methods used in measuring the component skills and the validity of subscores in designating areas for remedial instruction (the user must know what skills the pupil is expected to demonstrate), (2) an analysis of the reliability coefficients of the subscores (these must be above .90 for individual use), and (3) an analysis of the intercorrelations among subtests (these must be below .65 to warrant differential diagnosis). Because diagnostic tests are used primarily as a means of intra-individual diagnosis, accompanying test norms are not mandatory. The necessity of utilizing knowledge of a child's intelligence scores, scholastic ability, listening comprehension, and arithmetic computation, as well as his diagnostic test scores in planning a remedial program, is emphasized. (BS)