The study examined trends in the offense composition of inmates by age, gender, and jurisdiction. Between 1988 and 1998, the number of people in Australian prisons increased from 12,321 to 19,906, an increase of 62 percent. In 1988, 7.5 percent of the total inmate population was imprisoned for assault. In 1998, this figure increased to 12.6 percent. In 1988, 25 percent of the inmate population was imprisoned for break and enter or theft. In 1998, this figure decreased to 19.1 percent. For females, there was an increase in the proportion imprisoned for assault, from 3.4 percent in 1988 to 10.4 percent in 1998. The proportion of females imprisoned for drug offenses fell from 16.1 percent to 11.8 percent. Inmates in the 20-34 age range increased their contribution to the total number of inmates imprisoned for assault. Older inmates were held for sex offenses more than for any other offense. Of inmates between 50 and 64 years of age, 38.9 percent were imprisoned for sex offenses in 1998, compared to 18.5 percent in 1988. For those aged 65 years and over, 56.9 percent were imprisoned for sex offenses, compared to 23.1 percent in 1988. In general, the offense composition of Australian prison populations remained stable over the 10 years between 1988 and 1998, despite some significant changes in individual offenses including assault and sexual assault. 7 references, 2 notes, 5 tables, and 1 figure