In Tennessee a law came into force January 1, 1978 requiring parents to use child restraints properly when transporting their children who are less than four years old. Alternatively, the law permits children to be held in arms, a practice known to be hazardous rather than protective. Before and after the law went into force, observations were made of children in cars exiting from shopping centers in Knoxville and Nashville, Tennessee, and in Lexington and Louisville, Kentucky, an adjacent state not having a child restraint law. More than 80 per cent of Tennessee children observed in the fourth month the law was in force were not using child restraints anchored by seat belts, although use rates increased in Tennessee (8 to 16 per cent) to a greater extent than in Kentucky (11 to 15 per cent). Moreover, due to a large increase in children traveling in arms in Nashville, there was an increase in such travel in the two Tennessee cities studied (23 to 28 per cent) relative to a decrease in those studied in Kentucky (19 to 14 per cent).