Effective interventions for early childhood, specifically, birth through three years old, are rooted in the parent-child relationship. Play is the natural language of children. The cognitive ability of children determines the level at which they can engage in, and benefit from, certain forms of therapy. Child-centered play therapy is rooted in person-centered theory, while using play as the primary form of communication between therapist and child. Filial therapy is thus a blended intervention in which education, group process, and play sessions are used to help parents to build emotionally enhancing relationships with their children. Teacher-child relationship interventions have also been derived from the filial model. These programs seek to help teachers to build positive relationships with students by practicing skills in play sessions and generalizing responses to the classroom. Adlerian play therapy is the application of individual psychology, to play therapy. Gestalt play therapy views the child as a holistic organism.