Nearly every state is engaged in standards-based reform, as seen by the development of statewide academic goals and guidelines in core subjects and the subsequent new state tests that will measure students' progress toward achieving these goals. A Study Group on Statewide Assessment Systems formed by the National Association of State Boards of Education (NASBE) explored issues related to standards-based reform and the assessment that supports it. This article reviews the Study Group's conception of the purposes of state assessments and uses these to build a framework for the essential characteristics of effective assessment systems. The ultimate goal of state standards and assessments is not to sort students into "haves" and "have nots" of knowledge, but to enable all students to meet the standards. An effective assessment system: (1) is aligned with rigorous state standards; (2) addresses specific goals and purposes; (3) balances validity, reliability, and efficiency; (4) inform instruction and providing for consequences; (5) has mechanisms to encourage schools and districts to align their instruction and evaluation with the state system; and (6) has a clearly articulated relationship with national measures of student performance. The NASBE Study Group was emphatic that state boards need to monitor the implementation of standards and assessment policies to ensure that their policy vision is realized. (SLD)