In an experimental study designed to investigate a decision-making model of seat-belt use, 227 employees of an agrochemical company participated in a health information program in which they watched either a videotape on seat belts or a control videotape and completed questionnaires immediately afterward and at 3 months and 1 year after exposure. In terms of total effects, the seat-belt videotape influenced beliefs, fear, and intentions assessed immediately after exposure, but had no effect on self-reported frequency of belt use at 3 months or 1 year. A full path analysis indicated some support for the decision-making model. In particular, probability difference (the perceived reduction in risk of death or serious injury due to wearing a belt) had a large influence on intentions to wear a belt and partly mediated the effect of the videotape on intentions. Reported frequency of belt use at 3 months was influenced both by post-test intentions and by initial frequency of belt use. Similarly, belt use at 1 year was affected by belt use at 3 months and by initial belt use. The findings are discussed in terms of the role of subjective probabilities and habitual factors in seat-belt use.