Matrix sampling of test items, the division of a set of items into different versions of a test form, is used by several large-scale testing programs. This Digest discusses nine categories of costs associated with matrix sampling. These categories are: (1) development costs; (2) materials costs; (3) administration costs; (4) educational costs; (5) scoring costs; (6) reliability costs; (7) comparability costs; (8) validity costs; and (9) reporting costs. These categories will vary in importance depending on the testing program. (SLD)