When confronted with the task of moving information on a CRT display, what factors affect the decision to use a window or scroll method? This experiment examined 79 users' decisions to scroll or window based on the type of data, pattern, and movement on a CRT display. Subjects with experience in the control of data on a display preferred to scroll. A significantly greater proportion of users chose to scroll when they were familiar with the pattern displayed and when the movement was constrained within the boundary of the screen. The type of movement also significantly affected the time required to indicate whether the movement was due to scrolling or windowing.