The history of good time provisions can be divided into three periods: 1817-1876, 1876-1971, and 1971 to the present time. In the first period, the major factors behind the creation of good time were to control prisoners, to regulate prison population, and to enhance the rehabilitation potential of inmates. In the second stage, parole coexisted with good time and good time generally was reduced in importance. During the most recent phase, good time has reemerged as a significant element in the sentencing and correctional process. However, the actual role of good time depends on many factors, including the level of prison overcrowding. (Author abstract)