The roles of the teacher and clinician in the diagnostic reading situation are explored, and the importance of diagnosis for reading instruction is stressed. Emphasis on a child-centered program, with the classroom and the clinic viewed as basic structures for gathering diagnostic information, is recommended. Factors related to reliability, validity, and interpretation of information are also discussed. Strang's seven levels of diagnosis are listed to indicate the responsibilities of the classroom teacher as compared with those of the clinician. It is noted that a special report issued by the National Advisory Committee on Dyslexia and Other Related Reading Disorders (HEW) revealed that 15 percent of otherwise able students were experiencing difficulties in learning to read. The immediate concern indicated, then, is the discovery and treatment of these 8-million youngsters, a massive task that requires the training of individuals who can gather, analyze, and interpret the necessary data so that treatment may be applied. References are included. (WB)