A new national assessment system could lay a solid foundation for improving schools by monitoring the effectiveness of schools and teachers and student progress toward national goals. A sound national assessment system would: (1) allow valid comparisons between schools, districts, and states; (2) provide sound data on achievement, not just aptitude; (3) prod schools to focus on important performance-based outcomes; and (4) yield results for every important level of the educational system. A carefully designed national examination system can do all this without requiring a national curriculum, while increasing incentives for all students to achieve. Achievement tests should measure what we think is most important for students to learn. Tests are our primary source of information about educational achievement. Reliable information about achievement is needed so that schools can be held accountable for students' performance. Any proposed national examination must be part of a broader plan that integrates objectives, standards, teaching, assessment, and accountability for results. (Contains four references.) (SLD)