The survey was divided into two phases: the first was conducted in November 1971 and the second in February 1972. Between the first and second phases, legislation passed in the ACT made it an offense to drive with a blood-alcohol level in excess of 0.08 percent. A more severe penalty was provided for persons convicted of driving with a blood-alcohol level of 0.15 percent or more. Each of the two phases consisted of about 3,500 interviews accompanied by breath collection conducted over a period of 14 consecutive days by 4 interviewing teams per day at 64 sampling sites. Results showed that only a small proportion of driving while intoxicated (DWI) was done in Canberra at levels over the legal limit; and that the introduction of the Breathalyzer legislation did not affect the incidence of DWI. However, this did not necessarily mean that the legislation had no effect, because the survey did not measure driver performance or accident involvement. Analysis of offender characteristics revealed that DWI at high blood-alcohol levels was almost exclusively confined to males, and that its incidence varied significantly with age, with peaks occurring in the early 30's and again in the 50's. Drinking-driving patterns also varied markedly at different periods of the day. Four figures, 10 tables, and 1 reference are provided.