Parent-child interaction therapy is an effective means to prevent and correct children's mental problems. Interactive interventions shown to be effective share common features: the focus is on the support of the parent's sensitivity, positive guiding ability and reflective capability. Simultaneous participation of both parents in the therapy, application of video observation and affirmation of positive collaborative relationship with the parents seem to increase the efficacy of the intervention. The above-mentioned elements are utilized in an interactive therapy method called Theraplay.