Recent reports by the National Council of Teachers of Mathematics (NCTM), the National Research Council, the Mathematical Sciences Education Board, and the Board on Mathematical Sciences emphasize that coordinated improvement in the content of mathematics curriculum, classroom instruction, and teacher education is the key to improving mathematics education. Consequentially, methods of assessing students' mathematics achievement also need to be reevaluated. This bulletin focuses on the impact that assessment has and can have on mathematics curriculum and instruction. The bulletin is divided into two sections. The first section addresses assessment done by the teacher as part of classroom instruction. Topics discussed include: teacher competencies in assessment, assessment techniques as recommended by the NCTM, reform of large-scale mathematics testing, and the need for equal opportunities for all students to learn mathematics. The second section discusses the impact that certain uses of large-scale testing can have on curriculum revision efforts. Topics discussed include: the perception of testing as a gatekeeper to curriculum reform and the revision of standardized tests to reflect current curricular reforms. A list of 36 references is included. (MDH)