Parent-child interaction therapy (PCIT), a manualized evidence-based intervention, was originally developed to treat disruptive behavior problems in children aged 2–6 years. It is also considered to be an evidence-based intervention for physical abuse among children. Moreover, PCIT has proved to be effective for attention deficit hyperactivity disorder, autism spectrum disorder, separation anxiety disorder, and depression. Thus, it could become the first evidence-based, transdiagnostic intervention method for 2–6-year-old children. PCIT is based on attachment theory as well as learning theory, combining aspects of play therapy and behavior therapy. It consists of two treatment phases: child-directed interaction (CDI) and parent-directed interaction (PDI). In both phases parents are taught special skills. When interacting with their child parents practice these skills and are live coached by the therapist. CDI aims at improving the parent-child relationship and is the basis for PDI. In CDI, parents learn to follow their child’s lead as long as the child shows appropriate behavior. In PDI, parents practice effectively taking the lead wherever necessary. On average, it takes about 15–20 sessions to complete PCIT, which can be terminated as soon as the parents demonstrate a mastery of the skills, when child disruptive behavior has been reduced to clearly normal levels, and when the parents have become confident in managing child behavior on their own.