Some of the major findings of CSE's (Center for the Study of Evaluation) Test Use in Schools Project are synthesized and interpreted. The Project incorporated fieldwork and survey techniques to answer questions about the kinds of tests teachers administer in their classrooms, the kinds of information teachers need from tests to make decisions about their students, and how teachers use test information to make decisions. Data collected during the study are described and interpreted from the standpoint of teachers' routine assessment needs and practices. The classroom teacher is seen as a practical reasoner and decision maker who makes clinical use of assessment information to diagnose, prescribe, and monitor instruction. The tests teachers use most frequently are those that fit their practical circumstances: formal and informal measures they themselves construct or seek out for the information they provide; and curriculum embedded tests that come with commercial or district materials. Policy implications germane to the development of testing programs are presented and features of a testing system that could be directly useful to teachers are described. (LC)