The development of curriculum frameworks for mathematics and science was an essential first step in the Third International Mathematics and Science Study (TIMSS). The frameworks have served as guides for the design of the achievement testing component of TIMSS, and as the foundation upon which the curriculum analysis component of the study is based. The goal of this monograph is to explicate those frameworks, to trace the process of their development as part of the overall TIMSS project, and to show where the frameworks and the curriculum analysis fit into the study as a whole. Chapter 1 is an introduction to TIMSS, and chapter 2 contains an overview of the study as a whole, as well as a description of the conceptual framework and related research questions. Chapter 3 includes a description of the structure of the frameworks and presents some suggestions about ways in which the frameworks might be used to provide rich descriptions of student outcome data. The frameworks themselves are presented in the appendices. Contains 34 references. (MKR)