Research indicates that belt wearing rates increase after belt law enactment and that postlaw wearing rates settle to values higher than prelaw rates but lower than initial postlaw rates. Belt wearing rates are influenced by enforcement levels. The most optimistic future scenario is that most or all States will have belt laws; there will be more States with primary enforcement laws, widespread efforts to maximize belt usage, and widespread availability of air bags. Two commentaries accompany this paper. One commentary argues that traffic safety research should acquire more of the method, style, values, attitudes, and institutional structures of the traditional sciences. The second commentary examines factors in the repeal of the Massachusetts belt use law, suggesting that States like Massachusetts, with secondary enforcement, minimal penalties, and low belt use, are vulnerable to repeal. 4 tables, 74 references.