The project to develop a diagnostic test for adults attending literacy classes was conducted in two phases. First, an Adult Informal Reading Test (AIRT) was administered, scored and interpreted by the project team. These results and guidelines for the advancement of adults in reading materials were communicated to cooperating project teachers, who then conducted the test with a nationwide sample of adults. The tests were scored and interpreted by the project team. Although the national test population was less than half the desired number, it seemed consonant with national statistics collected at the same time. Several areas of investigation led to inconclusive results because of the decline in the sample population size, but it was determined that the project did not succeed in identifying an instructional placement level through the use of the AIRT. Changes in word recognition, accuracy, rate and comprehension of material read orally among adults with similar instructional programs and AIRT pre-test scores varied. It was concluded that the AIRT must still be used primarily as an instrument to measure specific reading performances. (Two forms of the AIRT, relevant data on reading level of the materials, population distribution, and reading scores, are included in the appendix.) (AG)