The movement to strengthen the nation's workforce by redefining what all students need to learn has profound implications for the design of state assessment systems. The confluence of events--the change in the national and international climate, acknowledgment of long-standing inequities in education opportunity and achievement, and the recognition of constraints inherent in current assessment and accountability systems--prompted the National Association of State Boards of Education (NASBE) to convene a year-long Study Group to examine assessment systems for the 21st century learner. The Study Group considered a number of key questions as to how to design assessment systems that would capture complex high-level skills and deep content knowledge while providing meaningful information about students' progress and their specific learning and performance gaps. These questions include: (1) How do school boards create assessment and accountability systems that reflect what they really want students to know and be able to do and that incorporate the latest research about teaching and learning?; (2) How can they rethink the core standards in terms of how they contribute to students' abilities to be successful?; (3) What can they learn from high-performing nations about the design of coherent assessment systems?; (4) How should they redesign their assessment systems and what are the implications of these changes for each level of the system (state, district, school, and classroom)?; (5) What are the implications of these new assessments for helping teachers develop highly effective instructional practices (which involve calibration and differentiation of teaching in response to the level of individual students' learning)?; (6) What are the implications for higher education teacher and administrator development programs?; and (7) What are the accountability issues that must be addressed as the purposes and expectations for PK-16 systems evolve? Their conclusions and recommendations are presented in this report. Appendices include: (1) Glossary of Assessment Terms; (2) State Actions in Assessment and Accountability; and (3) Bibliography. (Contains 166 endnotes.)