This study investigated the extent of agreement between MicroPROUST, a prototype microcomputer-based expert scoring system, and human readers for two Advanced Placement Computer Science free-response items. To assess agreement, a balanced incomplete block design was used with 2 groups of 4 readers grading 43 student solutions to the first problem and 45 solutions to the second. Results showed MicroPROUST to be unable to grade a significant portion of solutions, but to perform impressively on those solutions it could analyze. For one problem, MicroPROUST assigned grades and diagnostic comments similar to those assigned by readers. For the other problem, MicroPROUST's agreement with readers on grades was lower than the agreement of readers among themselves, its grades were higher, and it gave fewer comments, particularly on structure and style. The extent of disagreement on grades, however, was small and much of the disagreement disappeared when papers were rescored discounting style. Three appendixes present programming problems, examples of student solutions and comments, and scoring rubrics. (Contains 10 tables and 13 references.) (SLD)