The relationship between one’s attachment style and the onset and other aspects of adolescent’s sexual behaviors is the focus of the present research. It is argued that anxious/ambivalent individuals, constantly seeking external reassurance, should have an earlier onset and more frequent sexual behaviors than the attachment types. One the contrast, securely attached individuals would have the least rate of premarital sexual behaviors. Based on the cluster sampling process, a sample of 408 teenagers was drawn from the population-senior students in all the 7 junior colleges in Taipei City 1997. it was found that ambivalent attachment was negatively related to the subjects’ sexual experiences and behaviors. This association is however, limited to the male teenagers only. Therefore, it was concluded that one can predict a teenage males’ sexual experiences and behaviors based on their attachment style. Teenage females’ attachment, however, cannot be predicted by there attachment style. A gender role explanation was provided to discuss this finding.