The purpose of this study was to determine whether collective bargaining significantly affects teacher time, particularly time spent in instruction and preparation. The study was based on recent research indicating that student achievement is affected by the time teachers spend in these areas. Researchers divided the activities performed by elementary teachers into five categories: (1) instruction; (2) preparation; (3) administrative and clerical duties, including meetings; (4) parent conferences; and (5) other noninstructional duties, primarily after-school activities. The central finding of the study, based on a national survey of over 3,000 elementary teachers in nearly 250 districts, was that teachers covered by collective bargaining spend approximately 3 percent less time in instruction per day (or 1 week less per year) than teachers not covered by collective bargaining. Whether or not this reduction in instruction leads to a decline in the quality of schools cannot be answered on the basis of this study. What can be said based on this study is that collective bargaining may have a tendency to reduce student achievement by reducing time spent in instruction. (Author/LL)