Demand for information on the effects and returns of preventive interventions in the welfare sector has been steadily growing for some years now. SEO Economic Research carried out cost-benefit analyses of seven welfare projects for MOgroep Welzijn & Maatschappelijke Dienstverlening (the trade association for welfare and social services). This scientific literature survey looked mainly at projects in other countries that are similar to Dutch projects and approaches used in the Netherlands. Five of the seven welfare projects examined showed a clear positive return: participants in the projects became healthier or less depressed, displayed less risky behaviour or had their financial problems solved.