The authors take two goals often embraced by boot-camp practitioners -- treatment and prison population reduction -- and based on logic, research findings, and practical experience in running boot camps, develop two models for future boot camps. The two models are a "hybrid" model and a "treatment" model. The primary goal of the hybrid model is to reduce the prison population below the level it would have attained if the boot camp did not exist. Although boot camps typically cost more per inmate per day than regular prison, aggregate costs might be reduced by confining boot camp inmates for substantially fewer days than regular inmates and by reducing the capital expenditure for more prison construction. For either means to work, inmates who complete the boot camp must be confined for substantially shorter periods than they would have served otherwise. The secondary goal of the hybrid model is to rehabilitate offenders. Hybrid boot camps emphasize treatment to reduce recidivism, so as to prevent bed-space savings from being quickly eroded by graduates who fail upon release and are revoked and imprisoned. The primary goal of the treatment boot camp is to rehabilitate offenders. Officials may want to know what effect a treatment boot camp has on prison or jail populations, but only to plan for providing required resources rather than to assess whether the boot camp is effective. Rehabilitation effects may occur in two ways. First, the disciplined regimen of the camp may itself have a rehabilitation effect by increasing offenders' respect for authority, self-esteem, or self-confidence. Second, treatment programs and services may help offenders remedy problems such as drug abuse, lack of education, lack of employment, and family dysfunction that may have contributed to their prior criminality. The location, program elements, and aftercare of the two models are similar. They differ on goals, operating agencies, target population, screening criteria, evaluation, and program length.