Although the use of test results to demonstrate educational shortcomings is important, tests and assessments are also expected to be an instrument of reform. In fact, they are often expected to provide the primary means of creating educational reform. The minimum competency testing movement and the expansion of the use of test results for accountability purposes have been recent waves of test-based reform. The most recent wave of reform continues to emphasize accountability, but adds emphasis on using forms of assessment that require students to perform more substantial tasks than merely selecting multiple-choice items (performance assessment). Standards that shape assessment and define acceptable levels of performance and that insist on the inclusion of all students are also being advocated. Such standards are supported by the Goals 2000 legislation, as are the most controversial standards in the Goals, those of opportunity-to-learn (OTL). OTL standards are being demanded by those who feel that it is not fair to hold students accountable for meeting performance standards unless they have been given adequate opportunity to meet them. OTL standards pose daunting measurement challenges that will be increased by high-stakes use. (Contains 1 table, 2 figures, and 37 references.) (SLD)