Performance feedback and supervision are essential to the adoption of evidence-based interventions with high treatment integrity in child and youth care organizations. Little is known about the use of treatment integrity measurements in these organizations. For this study, 12 interventions for children and young people in the Netherlands with externalizing behavioral problems were selected. For each intervention, an expert, two supervisors, and two therapists were approached for an interview. In total, 54 semi-structured interviews were conducted. The results show that almost all interventions used treatment integrity instruments (N = 11, 91.7%). Only two used measurements for both QA procedures (certification and recertification) and supervision purposes. Therapists regard treatment integrity measurements as valuable when they are used for multiple purposes and feedback is provided. The results of this study suggest the feasibility of the use of measurements for multiple purposes. Collaborative action is required to develop instruments that effectively contribute to continuous improvement.