This study tested the validity and reliability of the West Informal Reading Evaluation (WIRE), an unobtrusive screening device that identifies adult learners' reading abilities. Of the 154 students in basic education or high school completion courses who completed one form of WIRE, 123 subjects were administered another reading test that served as the validity criterion, and 100 subjects were administered a second form of WIRE to determine the instrument's reliability. Results indicate that both WIRE forms are valid measures of adult silent-reading comprehension and yield reliable scores for the informal assessment of adult reading levels. The study concludes that reading teachers can use WIRE to select initial instructional materials, to select more-specific diagnostic instruments, to survey students in adult reading classes, and to assign students to adult reading classes. (RL)