While the use of safety restraints effectively reduces the risk of death or injury in accidents, many children still travel unrestrained in motor vehicles. Compulsory seat belt legislation in Australia increased rates of adult use dramatically, but did not have the same impact with children. In order to understand why levels of children's restraint use remain low, it is necessary to investigate parental factors related to use and non-use of restraints. This study assessed the rates of safety restraint use of parents and their pre-school children, and the sociodemographic, attitudinal and belief characteristics of parents which relate to children's restraint use, using the Health Belief Model as a basis for investigation. Restraint use for adults was substantially higher than for pre-school children. Children were more likely to be restrained if their parents were wearing seat belts, were married, were of high socioeconomic status, did not smoke, engaged in certain other preventive health behaviors on their children's behalf, traveled longer distances to pre-school and provided child seats for their children. In terms of the Health Belief Model, parents of restrained and unrestrained children differed in their evaluation of the "costs" and "benefits" of using restraints for their children, and in health locus of control. Parents of unrestrained children perceived the "costs" of restraint use, in terms of nuisance value, installation difficulty and financial cost, to be high. They were also less likely to believe that they could play a significant role in preventing injury to their children. Implications of these findings for safety restraint campaigns are discussed.