Ice velocity, net mass budget, and surface elevation change data were collected from 1957 to 1964 over the length and width of South Cascade Glacier, a small valley glacier 3.4 km long. Ice velocities range up to about 20 mi per year and three prominent velocity maxima along the length correspond to maxima in surface slope. The glacier flows in a slightly serpentine northwest direction and terminates in a lake. Changes in thickness of a glacier result from variations in velocity and strain as well as net budget. South Cascade Glacier loses ice first because of terminus recession, calving of ice into the lake, and change in the area near the terminus with narrowing of the glacier tongue, and second because of changes in elevation of the ice surface over the rest of the glacier area.