This monograph presents the findings of a multiyear study of the effectiveness of reform-oriented mathematics and science instruction. It builds on an earlier RAND study, called the Mosaic project, which found "a weak but positive relationship" between reform practices and student achievement (see Klein, Hamilton, McCaffrey, Stecher, Robyn, and Burroughs, 2000; Hamilton, McCaffrey, Stecher, Klein, Robyn, and Bugliari, 2003). The present study, called Mosaic II, extends this earlier research in two important ways. First, it incorporates more diverse indicators of student exposure to reform-oriented practices, including innovative, vignette-based measures. Second, it follows students for three years to measure the relationship after longer exposure. Similar to the earlier research, this study uses multiple measures of achievement, including open-ended assessments, to determine whether the relationship is sensitive to the manner in which achievement is measured. This monograph begins with a Preface, followed by a list of Figures and Tables, Summary, Acknowledgments and Abbreviations. The report is divided into the following five chapters: (1) Introduction; (2) Sample Selection and Data Collection; (3) Measures of Teaching Practices; (4) Relationships Between Reform-Oriented Instruction and Student Achievement in Mathematics and Science; and (5) Implications. Appendixes are included in a CD-ROM attached to the inside cover of this monograph. (Contains 6 figures and 12 tables.)