The National Highway Traffic Safety Administration estimates that a quarter of a million persons were killed in alcohol-related motor vehicle crashes over the past decade. Each year, more than 650,000 persons are injured in such crashes. Data provided to the Federal Bureau of Investigation (FBI) by State and local agencies indicate that between 1970 and 1986, DUI arrests rose more than 127 percent, while the number of licensed drivers rose by 42 percent. Arrests were highest among 21-year-olds, peaking at a rate of 1 for every 39 drivers of that age in 1983. Data are given for DUI arrests in relation to legislative changes and for DWI offenders in jail. The technique for determining blood alcohol concentration (BAC) is explained. The portion of the study relating to jail inmates is based on self-report data from the 1983 Survey of Inmates of Local Jails. A multistage stratified sample of 407 jails yielded a random sample of 5,878 inmates selected for personal interviews. Results show that 95 percent of those in jail for DWI were male, had a median age of 32, and reflected a racial distribution similar to the adult general population. Findings indicate that nearly half of all inmates in jail for DWI had previously been involved in an alcohol abuse treatment program. Tabular data and 19 references.