The sample consisted of 182 inmates admitted to prison over a 2-week period (April 26 through May 9, 1990). Almost all inmates (97 percent) had tried at least one of the drugs most often illegally used. Most inmates were using drugs more often than once a week in the 12 months prior to imprisonment. Seventy percent of the sample reported using drugs in the 24 hours preceding their offense. Sixty-two percent stated their current offense was related to their use of alcohol or other drugs. Seventy-four percent previously sentenced stated that either their previous or their current imprisonment was related to alcohol or other drugs. Of the inmates consuming drugs prior to their offense, those consuming alcohol were more likely than inmates consuming other drugs to report committing offenses such as homicide, assault, or other similar offenses. Fifty-nine percent of inmates stated that their use of alcohol or other drugs had caused them problems in the past 12 months. Thirty-two percent of inmates stated they were experiencing or expected to experience withdrawal from alcohol or other drugs upon being imprisoned. Recommendations are offered based on these findings. 16 tables, 14 references, and an appended drug-use questionnaire