This study examines the way the nation's educational system distributes opportunities to learn mathematics and science among various groups of students. Participation and achievement in mathematics and science by women, minorities, and the poor is disproportionately low. Minorities and the poor, especially in inner cities, have considerably fewer opportunities to learn science and math, largely because of the kinds of schools they attend. The section titles of this report are as follows: (1) "The Distribution of Opportunity"; (2) "The Effects of Student Characteristics on Opportunity"; (3) "Access to Science and Mathematics Programs"; (4) "Access to Qualified Science and Mathematics Teachers"; (5) "Access to Resources"; (6) "Classroom Opportunities: Curriculum Goals and Instruction"; and (7) "Implications." An appendix provides a classification of courses offered at the secondary schools included in the sample. A 133-item reference list is included. (DM)