The analysis considered recidivism rates, the duration of imprisonment, dismissal rates, and program capacity to assess the programs' impact if the probabilities that the offenders would have been in prison or on probation were varied. Different models were used to examine the impact of the shock program on prison crowding if 0 percent, 25 percent, 50 percent, 75 percent, or 100 percent of the shock entrants were taken from prison-bound entrants. Results indicated that the main factor driving the needs for prison beds is whether the shock incarceration program is used for prisoners or probationers. Findings indicated that if the goal of a short-term incarceration program is to reduce prison crowding, it must be carefully designed and monitored with this purpose in mind. Tables, figures, appended methodological information, notes, and 21 references (Author abstract modified)