The analysis is based on data collected by the Bureau of Justice Statistics from regular surveys of State and Federal prisons, as well as other national data sets. Results reveal that the growth in incarceration for drugs is driven most strongly by growth in arrest rates and then by commitments per arrest; some increase has occurred in time served, but only in the Federal system. No changes in arrests per reported offense and a net decline in offending rates have occurred for other offenses. The growth in State incarceration for nondrug offenses over the full study period is attributable entirely to sentencing increases, including 42 percent to commitments per arrests and 58 percent to time-served increases. New court commitments and parole violations have flattened out recently; the dominant contributor to current growth for all the offenses examined is time served. Incarceration rates rose 364 percent for women, 195 percent for men, 184 percent for black persons, 235 percent for Hispanics, and 164 percent for non-Hispanic white persons. The analysis concludes that benefits obtained from shifts up or down in sanctioning policy must be examined to establish sensible corrections policies and that knowledge about the benefits of incarceration in terms of the incapacitation and deterrence of crime is currently unavailable. 60 references (Author abstract modified)