According to this publication, a school's most effective tool in encouraging student success may be its control over the time the student spends working on goal-oriented learning activities--that is, time on task. This document is intended to help school administrators understand the effects of their decisions on students' learning time and improve those decisions. Research on learning time, reviewed in chapter 1, links the amount of learning time with the learning achieved. Chapter 2 discusses disruptions that arise outside the classroom and their effects on learning time; decisions made at the building, district, state, or federal levels may result in unexpected limits on the amount of time allocated for instruction. Chapters 3, 4, and 5 examine forces inside the classroom that can affect time on task: student behavior, teacher behavior, and instructional methods. The final chapter looks more deeply into the implications of the concept of time on task and at the roles of teachers, principals, superintendents, staff development personnel, and communicators in increasing time on task in schools. An appendix provides suggestions on how to develop a program to increase time on task within a school district and includes a step-by-step checklist and observation forms. (Author/PGD)