Abstract Model adherence is a key indicator of mental health care quality. This study investigates the degree of model adherence, as well as content and staging of care, among the first Youth Flexible Assertive Community Treatment (ACT) teams in the Netherlands. Model fidelity was assessed in sixteen teams with the Youth Flexile ACT model fidelity scale (2014 version). Mental health workers completed a ‘content of care questionnaire’ to map the interventions applied in the teams. Model fidelity scores revealed that twelve teams adhered to the Youth Flexible ACT standard with ‘optimal implementation’ (≥ 4.1 on a 5 point scale) and four teams with ‘adequate implementation’. Most disciplines were well integrated within the teams; however, several items regarding the involvement of specific disciplines and the availability of treatment interventions (peer support worker, employment and education specialist and programs, family interventions, integrated dual disorder treatment) scored below the optimum. Frequency of contact during ACT and the use of Routine Outcome Monitoring instruments scored below the optimum as well. The ‘content of care’ data showed that most clients received an individual psychological intervention, and nearly half of the client sample received scaled-up / intensified ACT care. The findings indicate a predominantly successful translation of care from the theoretical Flexible ACT framework into practice, covering both ACT and non-ACT functions. Further room for improvement lies in the incorporation of specialized disciplines in the personal and social recovery domains, including the peer support worker and employment and education specialist, as well as in specific protocolled interventions.