For 3 years, the National Center on Addiction and Substance Abuse at Columbia University (CASA) had been examining and probing all available data on the people in prisons; surveying and interviewing State and Federal corrections officials, prosecutors, and law enforcement officers; testing programs for substance-abusing offenders; and reviewing relevant studies and literature. To date, this had been the most penetrating analysis ever attempted of the relationship of alcohol and drug abuse and addiction to the character and size of America's prison population. This analysis found that 80 percent of the men and women in prison were seriously involved with drug and alcohol abuse and the crimes it spawned. These inmates numbered more than the individual populations of 12 of the 50 States; they were the parents of 2.4 million children, many of them minors. Among the other findings of the study were that the explosion of the inmate population was drug-related and alcohol-related; the more often an individual was imprisoned, the more likely that individual was a drug or alcohol addict or abuser; and there was a growing gap between inmate need for substance abuse treatment and access to such treatment. Given the general finding that well-designed drug treatment programs can be effective in reducing drug abuse, the prevention of drug and alcohol abuse and the provision of effective treatment for drug-and alcohol-abusing inmates hold the promise of significant savings to taxpayers and reductions in crime.