This exploratory, observational study was designed to reveal descriptive information regarding therapists' actual practices with preschool- and school-aged children in a single session of family therapy and to investigate change mechanisms in family play therapy that have been proposed to make this approach effective. A purposive sample of 30 families receiving family therapy was recruited and video-taped during a family session where at least one child between the ages of 4 and 12 was present. Following the session, the therapist and parent(s) completed questionnaires while one of the children (aged 4–12) was interviewed. Session recordings were coded, minute-by-minute, for participant talk time, visual aids or props used, and therapy technique type (e.g., play-based/activity vs. talk-only techniques). Hierarchical regression and canonical correlational analyses revealed evidence supporting the theory that play-based techniques promote young children's participation, enhance the quality of the child–therapist relationship, and build positive emotional experiences in family therapy.