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.