This analysis is based on U.S. Bureau of Justice Statistics for State and Federal inmates for each year from 1980 through 2000. From 1980 to 2000, the number of sentenced drug offenders increased more than 13 times, from 23,749 to 314,998. Between 1980 and 1990, the number of drug offenders in U.S. prisons increased annually by an average of 22.5 percent and never less than 10 percent. The increase was sharpest between 1987 and 1990, when it ranged from 27 percent to 48 percent. When viewed as a proportion of total inmates, however, the trend had a different complexion. From less than 10 percent in the early 1980's, drug offenders rose to and stayed at a level of approximately one-quarter of sentenced inmates for the first half of the 1990's. The proportion of drug offenders in U.S. prisons in 2000 was the same as in 1990 (to within 0.3 percent). In recent years, changes in the prison population have been driven less by drug offenders and more by inmates incarcerated for other offenses. In discussing possible explanations for the stable and declining proportion of drug offenders in prison, this article focuses on reporting and/or recording changes, the diversion of drug offenders, community re-entry, stabilization of the global illicit drug market, the shortening of sentence lengths for drug offenders, presidential terms, and change that relates to non-drug-offense inmates. 4 notes, 5 references, 3 figures, and 1 table