減少青少年在搭機車時因發生交通事故而造成頭部傷害最好的方法，就是提高他們搭機車戴安全帽的比率。雖然立法可以立竿見影，但是從青少年長期行為改變與持續的觀點，瞭解他們搭機車戴安全帽之影響因素與途徑則是這項工作之重點所在。本研究係採用兩個階段之前瞻性研究法，以理性行動理論與延伸之模式為此問題之思考架構。結果發現延伸之模式比理性行動理論、計劃行為理論對行為意向與行為的預測都來得適切，而行為控制信念是影響行為意向之最主要變項，其它依序為自我效能，態度與主觀規範，至於行為的立即決定因子則是行為意向，其它依序是行為控制信念、自我效能。若再多考慮過去行為，則它不僅可以影響行為意向，而且是此行為的唯一決定因子。

　　　　　The best strategy to reduce head injury among adolescent motorcycle passengers is to increase the rate of their helmet use. Mandatory helmet wearing can make a direct effect on this rate. However, from the viewpoint of long-term behavior modification and maintenance, it is very important to investigate the influential factors of helmet use among them, and that is the major purpose of this study. Under a two-wave prospective design, six scales with better reliability and validity were administered to 1,396 students sampled from all senior high schools for the academic year of 1996-1997 in Taiwan via a multi-stage stratified cluster random sampling method with pps. It was found that an extension of the theory of reasoned action( TRA)was better than TRA and the theory of planned behavior (TPB) in predicting behavioral intention and behavior of helmet use among them. In this model, perceived behavioral control was the major predictor in behavioral intention of helmet use among them, and other important variables were self-efficacy, attitude, and subjective norms. Behavioral intention was an immediate determinant to predict this actual behavior of helmet use, and perceived behavioral control and self-efficacy were also two influential factors. Again, past behavior was not only an important variable of this behavioral intention, but it was also the only, best single variable which had an independent influence on helmet use.