Background: In a semi-residential setting where children switch daily between treatment and home, establishment of a strong parent-team alliance can be a challenge. The development of alliance with parents and the symptoms of the child might be strengthened by a structured investment of treatment team members. Methods: Participants were caregivers and treatment team members of 46 children (6-12 years) who received semi-residential psychiatric treatment. An A-B design was applied, in which the first 22 children were assigned to the comparison group receiving treatment as usual and the next 24 to the experimental group, where treatment team members used additional alliance-building strategies. Alliance and symptom questionnaires were filled out at three-month intervals during both treatment conditions. Parent-treatment team interactions, assessed on DVD, were coded according to members' adherence to these strategies. Results: Multilevel analyses (using MLwiN) showed that based on reports of primary caregivers and a case manager, the alliance-building strategies had a statistically significant effect on the strength of the therapeutic alliance between treatment team members and parents. In addition, primary caregivers in the experimental group reported significant less hyperactivity symptoms of their children. Conclusions: Despite the methodological challenge of examining therapeutic processes in this complex treatment setting, this study supports the benefits of structured investment in the parent-team alliance.