Less than one-fifth of the U.S. population consistently wears automobile seatbelts. Automatic seatbelts or air bags will be required in all new cars, unless States whose total population equals two-thirds of the nation's adopt mandatory seatbelt use laws by 1989, according to the U.S. Department of Transportation. In July 1984, New York State passed the first mandatory seatbelt law in the nation, followed by New Jersey, Illinois, Missouri, Michigan, and New Mexico. A telephone survey of 2,982 randomly selected drivers examined belt use and support for mandatory belt use laws in the six New England States. Drivers with little education and low income, younger drivers, and drivers who drove after heavy drinking or marijuana use, or both, were least likely to wear seatbelts. Beliefs that seatbelts are not effective in reducing injury risk and are uncomfortable were more common among those not wearing belts. Sixty percent of drivers favored a mandatory seatbelt use law. The most important predictors of opposition to a belt use law were beliefs that seatbelts are ineffective, inconvenient, and uncomfortable. Opposition was also more likely among persons who reported that they drove after marijuana use, or heavy drinking, or both, drove more miles per year, exhibited a low frequency of seatbelt use, and perceived a low probability of personal crash involvement.