This brief report uses data from five administrations of the Schools and Staffing Survey (SASS) to examine the distribution of weekly instructional hours by regular, full-time first- through fourth-grade teachers of self-contained classrooms in four subjects: English/reading/language arts; arithmetic/mathematics; social studies/history; and, science. Results show that combined teacher instructional time in the four subjects has increased between 1987-88 and 2003-04. However, examining each subject shows that this increase is largely due to an overall increase in the amount of instruction in English and mathematics. In the two most recent administrations, 1999-2000 and 2003-04, weekly teacher instructional hours in English increased while instructional time in mathematics, social studies, and science decreased. Despite the fluctuations in hours of instruction, total instructional time in the four subjects as a percentage of the student school week did not change significantly between 1987-88 and 2003-04; it was about 67 percent of the school week in each year. Standard error tables are appended. (Contains 7 tables, 1 figure, and 2 footnotes.) [This report was written by staff at the Education Statistics Services Institute (ESSI), which is funded by NCES and composed of staff from the American Institutes for Research (AIR) and a number of partner organizations.]