Background: The therapeutic alliance between multidisciplinary teams and parents within youth (semi) residential psychiatry is essential for the treatment process and forms a promising process variable for Routine Outcome Monitoring (ROM). No short evaluative instrument, however, is currently available to assess parent-team alliance. Objective: In this study, the Working Alliance Inventory-Short Version (WAV-12), a widely used alliance questionnaire, was adjusted to assess parent-team alliance from both a parent and team perspective within a youth residential setting. Psychometric properties, including factor structure and validity of the subscales, were explored. Methods: A sample of youth with mainly complex developmental disorders admitted to 11 inpatient and day patient units of a child and adolescent psychiatric institute participated in this study. The case manager involved with the youth and the primary caregiver of 87 youth completed the revised WAV-12 (WAV-12R). Results: The team version of the WAV-12R showed a good fit to the original conceptualized model, and distinguished Bond, Task and Goal scales. For the parents' version an adjusted model with Insight, Bond and combined Task/Goal scales had the best fit. The reliability and validity of the scales were shown to be good. Conclusions: This paper presents preliminary evidence that the parent and treatment team versions of the WAV-12R are psychometrically sound for assessing parent-team alliance within youth (semi) residential psychiatry in the Netherlands. The team and parents' versions of the WAV-12R are recommended instruments to complement outcome measures in ROM.