The following practical applications of item characteristic curve theory are discussed (or referenced): l) estimation of observed-score distributions and parameters (mean, variance, and reliability coefficient), 2) selecting items to build a conventional test, 3) redesigning a conventional test, 4) optimal item-scoring weights, 5) mastery testing, 6) tailored testing, 7) two-stage testing, 8) multilevel testing, 9) equating, 10) formula scoring , 11) determining whether two tests measure the same trait, 12) checking the appropriateness of a test for individual examinees, 13) measuring item bias towards minority or other groups. (48pp.)