The current trend toward site-based management in education, with its accompanying shift toward decision making at the individual school level, means new responsibilities and roles for principals. Principals are now required to be intimately involved in budgeting, personnel recruitment and hiring, selection of curricula and textbooks, and many other tasks. To meet accountability requirements, principals must become competent in measurement and the design of practical evaluations. The competencies principals must demonstrate in assessment and accountability under site-based management can be divided into: (1) basic measurement concepts, such as reliability, validity, test types, and performance assessment, including portfolios; (2) knowledge about the use of test data to improve instruction, including student test-taking skills and the purposes of testing; (3) basic evaluation concepts; and (4) the characteristics of a good testing program and criteria for judging assessment quality. (Contains 13 references.) (SLD)