Data are presented separately for incarceration rates in State and Federal correctional systems. Incarceration rates are examined separately for each of six offenses under State systems and five offenses under the Federal system. Other data reported pertain to time served, inmate characteristics, arrest rates, and conviction rates. At the State level, incarceration rates for drug offenses have far exceeded increases in incarceration rates for the other offenses examined. Under the Federal system, the likelihood of incarceration has increased for weapons and immigration offenses, and the time spent in prison has increased mainly for drug offenders and weapons offenders. In both State and Federal systems, incarceration rates have variously impacted subpopulations within each offense category. Across most offenses, incarceration rates for women have increased faster than those for men. In drug offenses, African-Americans have been incarcerated at a greater rate than white offenders. The researchers note that 8 percent of black males in their 20s are currently incarcerated for a variety of offenses. Overall, the researchers conclude, the growth in prison populations continues, primarily due to increases in the length of time served. Some of the policy questions identified are whether the benefits of incarceration justify the costs compared to the cost- benefits of alternatives to incarceration, and whether incapacitation benefits are worth the costs when time served extends into the age range when criminal behavior declines. Future research will explore the relationship between incarceration policies and crime rates.