Despite the tripling of the inmate population and dramatic demographic changes, the criminal records and drug use histories of inmates have remained unchanged. The article identifies factors behind this growth and compares trends since 1990 with changes recorded during the 1980s. Increasing percentages of inmates are African American or Hispanic; Hispanics represent the fastest growing minority group being imprisoned. Between 1990 and 1994 the number of inmates over age 65 in Federal prison increased by 51 percent, accounting for only 1 percent of the total increase in the Federal prison population. Twenty-two percent of State prisoners are serving time for drug offenses, compared with 6 percent prior to 1990. The article also presents statistics and discussion regarding: offenders' criminal histories; reported drug use; arrests; probabilities of incarceration; length of sentences; and speculations on the future. Notes, tables, references