Examines the effect of altering test difficulty on examinee ability measures and test length in a computer adaptive test. The 225 Ss were randomly assigned to 3 test difficulty conditions and given a variable length computer adaptive test. Examinees in the hard, medium, and easy test condition took a test targeted at the 50%, 60%, or 70% probability of correct response. The results show that altering the probability of a correct response does not affect estimation of examinee ability and that taking an easier computer adaptive test only slightly increases the number of items necessary to reach specified levels of precision. (PsycINFO Database Record (c) 2002 APA, all rights reserved).