Developing the Trends in International Mathematics and Science Study (TIMSS) 2007 Assessment Frameworks represents an extensive collaborative effort involving individuals and expert groups from more than 60 countries around the world. The document contains three frameworks for implementing TIMSS 2007--the Mathematics Framework, the Science Framework, and the Contextual Framework for questionnaires. It also provides an overview of the assessment design, including general parameters for item development. The TIMSS content frameworks for 2007 rely heavily on the extensive efforts expended to update the frameworks for 2003, when specific assessment objectives were developed for Grades 4 and 8. For 2007, there was a further effort to consolidate the major content domains and present them separately for the two grades, as follows: (1) Mathematics: Grade 4--Number, Geometric Shapes and Measures, Data Display; Grade 8--Number, Algebra, Geometry, Data and Chance Science; and (2) Science: Grade 4--Life Science, Physical Science, Earth Science; Grade 8--Biology, Chemistry, Physics, Earth Science. Both the mathematics and science assessment frameworks also have a cognitive dimension--Knowing, Applying, and Reasoning. To enable reporting by cognitive domains, these also were revised for TIMSS 2007 to sharpen the distinction among categories. Following a foreword and an introduction, this publication offers four chapters: (1) TIMSS 2007 Mathematics Framework; (2) TIMSS 2007 Science Framework; (3) TIMSS 2007 Contextual Framework; and (4) TIMSS 2007 Assessment Design. Appended are: (1) Acknowledgements; (2) Example Mathematics Items; and (3) Example Science Items. (Contains a list of 32 resources consulted.) [This document was also published by TIMSS & PIRLS International Study Center, Lynch School of Education, Boston College.]