This study gives an overview of Project STARS (Studies on Trajectories of Adolescent Relationships and Sexuality), a four-wave longitudinal study of 1297 Dutch adolescents. First, the sample, measures and four sub-projects are described. Second, hierarchical regression analyses were conducted to examine how key variables from the individual domain (impulsivity), parent domain (parent–adolescent relationship quality), peer domain (involvement with peers) and media domain (time spent on social networking sites), and their interactions predict changes in the experience with sexual behaviour of adolescents across time. Results showed that higher levels of impulsivity, lower quality of relation with parents, more frequent involvement with peers and more time spent on social networking sites at baseline predicted increases in sexual experience of adolescents over a subsequent 1.5-year time period. No interaction effects among the domains were found. The findings highlight the significance of a multi-domain approach to the study of adolescent sexual development.