A study used Marie Clay's complete diagnostic survey (diagnostic survey and recovery procedures from "Early Detection of Reading Difficulty") in two first-grade classrooms in order to ascertain class profiles for January and April of 1983, the reactions of teachers, instructional changes, and changes in the children's reading behaviors over that period of time. Fifty-two suburban first-graders were given the survey, consisting of six parts: (1) three word lists; (2) a running reading record; (3) a letter identification test; (4) "The Concepts about Print Test"; (5) a writing sample; and (6) a dictation test. Results yielded an extensive array of data showing in detail what knowledge, concepts, and strategies children possessed and were using in a number of categories of reading and writing behaviors. Instructional inferences can be made from these data for individual children, but a particular uniform skill hierarchy or sequence of behaviors for all children is not implied. Children's progress seemed to be closely related to reading strategy acquisition. Recommendations included the use of the survey not only for the early detection of reading difficulties, but also for developing teachers' observational skills and concepts of the reading process. (Six tables of data are included.) (SR)