As a result of a concern over the adequacy of teacher rating instruments, a project was begun to develop a pool of items describing teacher behavior. Most of the items were derived from the literature; some were written by the project. The item pool presently consists of 1137 items subsumed under 19 categories. Examples of categories are: personal and professional characteristics, motivation, discipline, lecturing, use of instructional materials, and discussions and small group work. In addition to this categorization, each item has been indexed by its key words and has been further classified as referring to behavior that is ratable, whose frequency is countable, or that can be treated in both ways. The item pool is stored on-line in an IBM 360/67 computer, and two programs are available for use. The first program allows the investigator to select the items he wishes to examine; it produces a listing of the items requested or a deck of cards with one item on each card. The second program generates rating forms which can be used in classroom observation. One form can include up to 25 items. It is suggested that future efforts focus on achieving a balance among the 19 item categories and developing the computer system. (The document includes a complete list of the 1137 items.) (RT)