本研究的目的在探討個人背景變項、同儕影響與促進因素對青少年參與身體活動行為意圖的影響。以臺北市某區公立國中學生為研究母群，經多步驟叢集抽樣，抽出四校，以其7、8、9年級學生為樣本，問卷發出681份，有效問卷回收率為84.1%。研究對象男生佔49.9%，女生佔48.2%。短期（一個月）與長期（六個月）參與身體活動行為意圖平均分數為2.41分與2.38分，是屬較低的行為意圖，其影響因素為性別、同儕影響及促進因素，預測變項可解釋短期行為意圖變異量的46.5%，預測變項可解釋長期行為意圖變異量的49.8%。建議：未來可對同儕影響進行縱貫式的觀察與研究，以了解其對於青少年身體活動的長期影響，另在規劃身體活動教育介入時，可參酌青少年的發展特質與環境設備。

The purposes of the study were to explore the effects of background variables, peer influence, and promoting factors on the behavioral intentions of adolescents that participated in physical activities. With the students of public junior high schools in a district in Taipei City as the population, by multiple step cluster sampling, a total of 681seventh, eighth, and ninth grade students in four schools completed questionnaires. The respondent rate was 84.1%.The results of the study are: the boys accounted for 49.9% and the girls accounted for 48.2%. The average scores of the short-term (one month) and long-term (six months) behavioral intentions of participated physical activities were 2.41 and 2.38, respectively, which were lower behavioral intentions. The influential factors include gender, peer influence, and promoting factors, while the predictors explained 46.5% of the short-term behavioral intention variance and 49.8% of the long-term behavioral intention variance. It is suggested that longitudinal observations and studies be conducted on peer influence in order to understand its long-term influence on physical activities of adolescents. Additionally, when planning physical activities related educational interventions, the developmental characteristics of adolescents and environmental equipments shall serve as a reference.