The purpose of this study was to describe the management of challenge during therapist-child interaction in sensory integration treatment. This descriptive and relational study of the middle minutes of treatment sessions partially replicated an earlier study of the beginning minutes. One minute Videotape clips taken from the middle minutes of 38 treatment sessions were shown to therapist judges who rated qualities of therapist and child behavior. Two patterns emerged from the correlations of ratings: work and playfulness. Work for the child involved trying hard, cooperating, and seeking assistance, whereas work for the therapist involved assisting and guiding the child. Play for the child included enjoying the activity, being successful and confident, and trying hard. For the therapist, play involved being creative and behaving playfully. Patterns of work and play were different across different levels of challenge to the child.