National Assessment of Educational Progress (NAEP) data for 9-, 13-, and 17-year-old students in the United States are provided, highlighting trends in science achievement from 1969-70 to 1990, mathematics achievement from 1973 to 1990, reading achievement from 1971 to 1990, and writing achievement from 1984 to 1990. Trends in academic proficiency for the nation and demographic subpopulations; trends in students' science and reading experiences and attitudes; patterns in school and home contexts for learning mathematics and reading; and trends in attitudes, behaviors, and instruction for writing are illustrated. Overall, the trends suggest few changes in educational achievement levels across the two decades covered by NAEP assessments. However, some declines in science and mathematics for 17-year-olds during the 1970s and generally low performance levels across several curriculum areas prompted reform efforts. Improvements occurred in science and mathematics during the 1980s at all three ages. Particularly for science, there is a pattern of decreased proficiency in the 1970s followed by recovery in the 1980s. Conversely, the reading results show that gains made by 9-year-olds in the 1970s eroded during the 1980s, while the performance of 13-year-olds remained constant. Writing achievement also showed some decline in the 1980s for eighth graders. Recent gains in mathematics and science achievement were partially offset by some losses in reading and writing. However, 17-year-olds improved their reading skills during the same period. Twenty-six figures and 64 data tables are provided. A procedural appendix summarizes procedures used in the 1990 trend assessments and provides 13 data tables. A data appendix provides 24 tables each showing science, mathematics, and reading trends; and 15 tables showing writing trends. (RLC)