A systematic probability sample was used in the survey. Up to four recalls were made to contact respondents who were all over the age of 16. Of 39 percent of the drivers spoken to by a police officer about a possible offense, 25 percent had been spoken to more than once in the previous 2 1/2 years. In most cases, the police officer spoke to them abut only one offense, the most common being speeding. In 44 percent of the cases, the officer gave a verbal warning, in 4 percent a warning letter was sent, and in 38 percent of the cases court action was followed. In 61 percent of the cases, drivers reported that they took more care subsequently. Warnings appeared to be as effective in this respect as court actions for some driving offenses, but for vehicle offenses court action appeared more effective. Data tables and five references are included. (Author abstract modified)