Background: The Development and Well-Being Assessment (DAWBA) has been used in various epidemiological studies whereas the clinical value of the instrument needs support from further studies. In particular, it is important to document how the use of the DAWBA influences clinical decision making. Methods: The present study employed the DAWBA in a consecutive series of 270 new referrals to a large public child and adolescent psychiatric service in Zurich, Switzerland. ICD-10 based diagnoses were obtained from clinicians for all patients and reliability of DAWBA expert raters was calculated. DAWBA diagnoses were randomly disclosed (N=144) or not disclosed (N=126) before clinical decision making. Results: The reliability of DAWBA expert diagnoses was very satisfactory and the agreement under the disclosed vs. the non-disclosed condition amounted to 77% vs. 68% for internalizing disorders and to 63% vs. 71% for externalizing disorders. The increment in agreement due to disclosure of the DAWBA diagnosis was significant for internalizing disorders. Access to DAWBA information was more likely to prompt clinicians to add an extra diagnosis. Professional background and degree of clinical experience did not affect diagnostic agreement. Conclusions: Overall, diagnostic agreements between DAWBA expert diagnoses and clinical diagnoses were in the fair to moderate range and comparable to previous studies with other structured diagnostic interviews. The inclusion of the DAWBA into the clinical assessment process had an impact on diagnostic decision making regarding internalizing disorders but not regarding externalizing disorders.