Education is a hot topic. From the White House to teh family dinner table, it is an issue that most Americans are deeply concerned about. While there are many strategies for improving the educational process, we need a way to find out what works and what doesn´t. Educational assessment seeks to determine just how well students are learning and is an integral part of our quest for improved education. The nation is pinning greater expectations on educational assessement than ever before. We look to these assessement tools when documenting whether students and institutions are truly meeting education goals. But we must stop and ask a crucial question: Given the multiple purposes for assessing student knowledge, what kinds of assessements are most effective for serving the needs of different audiences?. At a time when traditional testing is subject to increasing criticism, research suggests that new, exciting approaches to assessement may be on the horizon. Advances in the sciences of how people learn and how to measure such learning offer the hope of developing new kinds of assessement- assessements that help students succeed in school by making as clear as posible the nature of their accomplishments and the progress of their learning. Knowing What Students Know explains how expanding knowledge in the scientific fields of human learning and educational measurement can form the foundations of an improved approach to assessement. These advances suggest ways that the targets of assessement- what students know and how well they know it- as well as the methods uses to make inferences about student learning can be made more valid and instructionally useful. Principles for designing and using these new kinds of assessement are presented and examples are used to illustrate the principles. Special attention is givem to the role of technology in harnessing the power of these new approaches. Implications for policy, practice, and research are also explored. With the promise of higher quality information from new approaches to assessement based on contemporary theories of learning and its measurement, Knowing What Students Know will be vitally important to education administrators, assessement designers, teacher and teacher educators, and education advocates.