Online prevention aimed at lifestyle behaviors: some considerations the internet is used more and more frequently as a delivery mode for preventive interventions that offer support in people’s choices regarding health behavior. This article presents some considerations with regard to internet-delivered interventions regarding active ingredients, tailored advice, cost-effectiveness and professional support, and anonymity and use. The most important conclusions of this article are that practical applications in an online context of specific behavior change methods deserve future experimental studies. Interventions that make use of tailored advice could be developed further, in which actions from other participants are taken into account when generating advice. Evaluation studies should give a decisive answer about whether professional support contributes to use, effectiveness, and cost-effectiveness of internet-delivered interventions.