Conduct problems in childhood affect the daily lives of children and their families and have serious economic implications for society. The Incredible Years parent program (IY) is a manualized behavioral parent training that aims to improve parenting skills in order to reduce conduct problems of children. We conducted a cost-effectiveness analysis of IY, compared to care-as-usual (CAU), in preschoolers at risk for a chronic pattern of conduct problems. In a case-control design with a two-year follow-up, we assessed intervention costs, use of public services (e.g., healthcare and special education), property damage, travel costs, and parental productivity losses. Conduct problems reduced in children in the IY condition, relative to CAU. From the public authorities perspective, the net costs to reduce the child’s conduct problems by one point of observed conduct problems (meaning a reduction of one disruptive behavior each 20 minutes) were €187. Taking the parents’ perspective and the societal perspective it was €88 and €155, respectively