My reviews of the evidence base for family therapy conducted over the past 15 years have been guided by four key questions. Does systemic therapy work? What sorts of systemic therapy work for specific problems? What processes occur in effective systemic therapy? Is systemic therapy cost‐effective? In this paper answers to these questions are given. Systemic interventions are effective for about two out of three cases. Specific models of effective systemic therapy have been developed for most common mental health problems. There are many processes shared by evidence‐based models of practice that can be incorporated into the routine practice of research‐informed family therapy. Systemic therapy is cost‐effective and in many cases leads to medical cost‐offsets. Available evidence indicates that family therapy can make a very significant contribution to alleviating suffering and making the world a better place to be.