The study reported in this volume adds to the growing body of evaluation studies that focus on the use of NSF-funded Standards-based high school mathematics curricula. Most previous evaluations have studied the impact of field-test versions of a curriculum. Since these innovative curricula were so new at the time of many of these studies, students and teachers were relative novices in their use. These earlier studies were mainly one year or less in duration. Students in the comparison groups were typically from schools in which some classes used a Standards-based curriculum and other classes used a conventional curriculum, rather than using the Standards-based curriculum with all students as curriculum developers intended. The volume reports one of the first studies of the efficacy of Standards-based mathematics curricula with all of the following characteristics: (1) The study focused on fairly stable implementations of a first-edition Standards-based high school mathematics curriculum that was used by all students in each of three schools; (2) It involved students who experienced up to seven years of Standards-based mathematics curricula and instruction in middle school and high school; (3) It monitored students' mathematical achievement, beliefs, and attitudes for four years of high school and one year after graduation; (4) Prior to the study, many of the teachers had one or more years of experience teaching the Standards-based curriculum and/or professional development focusing on how to implement the curriculum well; and (5) In the study, variations in levels of implementation of the curriculum are described and related to student outcomes and teacher behavior variables. Following a preface and acknowledgments, this book contains: Part I: Background: (1) The Core-Plus Mathematics Curriculum: Design and Development; (2) Review of Related Literature; (3) Method and Procedures; (4) Teachers and the Curriculum; Part II: Yearly Patterns in Student Achievement: (5) Achievement Patterns in Year 1: Four Content Strands; (6) Achievement Patterns in Year 2: Algebra and Functions; (7) Achievement Patterns in Year 3: Mathematical Literacy; (8) Achievement Patterns in Year 4: Advanced Mathematics, Reasoning, and Proof; Part III: Attitudes, Beliefs, and Conceptions of Students: (9) Attitudes about the Curriculum and Pedagogy: Years 1 and 2; (10) Beliefs and Conceptions About Mathematics: Years 1-4; and Part IV: Post-High School Survey, Individual Cases, and Perspectives: (11) Performance in Post-High School Educational Institutions; (12) Longitudinal Experiences of Three Students. Description and Effects of a Local Controversy; (13) Summary and Interpretations.