In March 1973, 18 months after seat belt use became mandatory in NSW, 1251 people were interviewed in Sydney on their seat belt usage and attitudes. This survey was a repeat of a survey taken prior to the law, in March 1970, with a comparable sample. The 1973 follow up survey was designed to determine the extent to which the law had influenced wearing seat belt habits and attitudes. Reported wearing rate had increased dramatically. In 1973 3 out of 4 people reported always wearing a seat belt, compared to only 1 out of 4 in 1970. Only 1 in 10 people reported rarely or never wearing one in 1973, compared with 5 in 10 in 1970. This high level of compliance with the law was found in every sub group examined. Attitudes expressed by respondents indicated that seat belts are now fully accepted by the majority of the community. After the law, people were more likely to believe seat belts to be important to safety and negative attitudes were rare. In addition 8 out of 10 people were in favour of the law. Reasons for the law’s impact on behaviour and attitude, the relevance of enforcement activity and the future role of propaganda are discussed in the light of these survey results.