In Switzerland, recent years have witnessed an increasing frequency of intensive family support—known under the German term “sozialpädagogische Familienbegleitung”—with families who are seen as unable to take adequate care of their children and to provide them with the necessary conditions for positive emotional, cognitive, and social development. In the child protection system in particular, family support services are ever more frequently mandated by child protection authorities with the intention of preventing the more drastic measure of out-of-home placement. The services are delivered in the shape of intensive home-visitation, typically extending over a period of several months, where social workers visit the families in their homes on a weekly or near-weakly basis and work primarily with parents to encourage more positive attitudes towards parenting and more appropriate parenting styles.The main objective of our ongoing study, which is one of the first quasi-experimental field trials with regard to intensive family support services in a German-speaking country, is to rigorously assess the efficacy of these services, using structural equation modeling to investigate causal pathways connecting baseline characteristics of cases and attributes of the intervention to the intervention’s outcomes. More particularly, in the framework of a conditional process model, the research investigates the socio-economic, social and personal characteristics and resources of the families and its members, the observed risks and problems that supposedly necessitate the intervention, and the development of these phenomena over the course of the intervention and a subsequent follow-up period. Data collection tools encompass interviews and questionnaires addressed to social workers carrying out the intervention, and parents and their children receiving the services. The study involves an intervention and an comparison group. In addition, the research incorporates a mixed-methods sequential explanatory design, where the findings from the quantitative analyses will be discussed with frontline workers, child protection authority board members and parents and children in both homogeneous and mixed focus groups.