Measuring student progress toward higher achievement has been the purpose of the National Assessment of Educational Progress (NAEP) since its inception in 1969. Students in both public and nonpublic schools have been assessed in various subject areas on a regular basis. This report presents results of the 1994 NAEP trend assessments in science, mathematics, reading, and writing. To provide a numeric summary of students' performance on the assessment questions and tasks, the NAEP uses a 0-to-500 scale for each subject area. Nationally representative samples of approximately 31,000 students were involved in the NAEP 1994 trend assessments. Trend assessment results are included for each area, going back to: 1969-70 in science; 1973 in mathematics; 1971 in reading; and 1984 in writing. Trends are discussed for students at ages 9, 13, and 17 for science, mathematics, and reading, and for students in grades 4, 8, and 11 for writing. Trends in performance differences among ethnic and racial groups are also discussed. Tests of linear and quadratic trends were supplemented by a second set of statistical tests that compared results for selected pairs of assessment years within each trend sequence. In general, trends in science and mathematics show early declines or relative stability, followed by improved performance, but reading and writing results show few indications of positive trends. (Contains 4 figures and 10 tables.) (SLD)