This report describes participation, student characteristics, and achievement for 10 high school courses assessed by the North Carolina End-of-Course Testing Program in 1990-91. Subject areas are: (1) Algebra I; (2) Geometry; (3) Algebra II; (4) Economic, Legal, and Political Systems in Action (ELP); (5) U.S. History; (6) English I; (7) Physical Science; (8) Biology; (9) Chemistry; and (10) Physics. In 1990-91, 534,223 students took End-of-Course tests. Participation in advanced mathematics and science courses varies by sex, parental education, ethnic group, and post-high school plans. Overall achievement appears to be increasing slowly in Algebra I, Biology, and Chemistry. Average performance also differs by sex, ethnic group, parental education, post-high school plans, anticipated final grades, and school system. Results support the validity of the End-of-Course tests. Schools and school systems can identify strengths and weaknesses in instructional programs by examining relative performance on the items that these tests assess. In addition, the End-of-Course tests are part of three state accountability systems. Ten tables present information about student participation and achievement. Twenty-three figures present testing results in graph form. In addition, 32 pages of tables identify outstanding school systems and give results for 133 school systems. An appendix (10 pages of tables) lists core score distributions. (SLD)