It appears that in practice exposure to Internet-delivered behaviour change interventions, encouraging a healthy lifestyle for adolescents with regard to health risk behaviours, is quite low. There is, however, a lack of evidence-based insight into how to disseminate such interventions and how to reach optimal exposure. A more extensive exploration is therefore timely since this knowledge is crucial to improve the public health impact of such interventions. By means of a three-round Delphi study factors associated with dissemination of and exposure (first visit, stay long enough and revisit) to Internet-delivered interventions aimed at adolescents had been identified, as well as the extent to which experts agree on the importance of these f...