Possible causes of a 16-point mean score increase for the computer adaptive form of the College Level Academic Skills Test (CLAST) in reading over the paper-and-pencil test (PPT) in reading are examined. The adaptive form of the CLAST was used in a state-wide field test in which reading, writing, and computation scores for approximately 1,000 students were compared for the March or June 1988 administrations of the PPT and the spring of 1988 administration of the computer adaptive test (CAT) version. The field study data were analyzed to address measurement error, content coverage and reading load, and student motivation. A follow-up study used data from 361 community college freshmen and sophomore students who had taken the October 1989 or March 1990 paper-and-pencil version of the CLAST but had not yet received their scores; these subjects were administered the Nelson-Denny Reading Test, as well as the CAT form of the CLAST. The follow-up study failed to replicate the difference in mean scores for the computer adaptive and paper-and-pencil versions of the reading test that were found in the preliminary analysis. Overall results indicate that students should be allowed a longer testing period for the CAT version of the CLAST than for the PPT version. Seven data tables are included. (TJH)