Belt use among drivers traveling on limited access highways was observed before and after New York's mandatory seat belt use law. The results showed that high-speed drivers had lower belt use rates before the law and increased their belt use less in response to the law. Belt use rates before the law were 25%, 29%, and 28% for the high-, medium-, and low-speed groups as compared with 51%, 64%, and 57%, respectively, after the law. High-speed drivers also had inferior previous driving records, confirming their higher risk of motor vehicle crash involvement.