Sexual behaviour among adolescents is a major concern. Factors associated with the occurrence of sexual behaviours may differ according to many aspects including geographical and cultural context. Thus this study aimed to assess the sexual behaviour and related factors among the senior high school students in Singkawang municipality, West Kalimantan province, Indonesia.The study was done in February 2009; random sample of 300 students from 3 senior high schools were invited to participate in this cross-sectional survey. A self-administered questionnaire was developed and administered in classroom setting. This study used PRECEDE-PROCEED model. Factors assessed were predisposing factors, reinforcing factors, and enabling factors to sexual behaviours.