The National Assessment of Educational Progress (NAEP) evaluated the writing ability of American students in 1974, 1979, and 1984. Data from 95,000 students were examined for trends over this 10-year period. Writing tasks, including informative, persuasive, and literary or imaginative writing were administered to national samples of students aged 9, 13, and 17. The results indicated that, in general, achievement in 1984 seemed to be no better than it was in 1974. Achievement trends for Black, Hispanic, and White subgroups, as well as those defined by geographic region or sex, were similar to nationwide trends. From 1979 to 1984, students' writing skills showed improvement, particularly at ages 13 and 17. However, achievement remained low in 1984; only 38 percent of the 17-year olds produced a well-organized and detailed descriptive essay, and only 20 percent wrote an effective persuasive letter. Imaginative writing improved for all ages. Results also indicated that although greater attention was focused on writing instruction in 1984 than in 1974, the actual amount of writing done by students remained about the same. Data tables, graphs, a summary of NAEP procedures, and students' writing samples showing different levels of expertise are included. (GDC)