At the end of 1996, more than 1.7 million American adults were behind bars: 1,076,625 in State prisons, 105,544 in Federal prisons, and 518,492 in local jails. The study of the relationship between alcohol and drug abuse and the prison population included an analysis of data from national inmate surveys, a survey of State and Federal corrections officials and prosecutors, a review of programs for drug-abusing offenders, and a comprehensive review of the relevant research literature. It was determined most offenders, regardless of their crimes, had drug problems. Alcohol and drugs were implicated in increased rates of arrest, conviction, and imprisonment for property, violent, and drug offenders, the three major inmate groups. Drug abuse was strongly associated with recidivism. Alcohol was more closely associated with murder, rape, assault, and child and spousal abuse than illegal drugs. In State and Federal prisons, the gap between available drug treatment and inmate participation in such treatment was significant. Most inmates who were addicted to drugs also needed medical care, psychiatric help, and literacy and job training. Regular drug users in prisons and jails were more likely than the general inmate population to have a family member who served prison time. Of the $38 billion spent on prisons in 1996, more than $30 billion paid for the incarceration of individuals who had histories of drug and alcohol abuse, were convicted of drug and alcohol violations, were high on drugs and alcohol at the time of their crimes, or committed their crimes to get money to buy drugs. The importance of effective drug prevention programs is discussed, and recommendations to lower recidivism by reducing alcohol and drug abuse are offered. 32 references, 1 table, 1 figure, and 1 photograph