In an effort to evaluate the effects of the compulsory seat belt wearing legislation in New South Wales, data relating to observed wearing habits, public attitudes towards seat belts, traffic crash fatality and injury trends and reported traffic offences, were examined. It appears that seat belt wearing rates have increased and that there has been a favourable departure from the existing trend in motor vehicle occupant fatalities. Trends in crash injury data are discussed. The introduction of compulsion has also been accompanied by changes in public attitudes and by changes in patterns of reported traffic offences (a).