Co-play therapy is a technique designed to meet two challenges; (1) dealing with a play therapy case at a “stuck point” and (2) providing live supervision and modeling that allows a therapist-in-training to work with extremely difficult cases. In co-play therapy, two therapists work together, dividing the therapeutic role. One therapist plays directly with the child, as fully and intensely as seems appropriate. The other comments on their interaction and sets limits. This paper presents two illustrative cases and gives guidelines for conducting co-play therapy.