Objective: Existing patient-reported outcome measures (PROM)s for patients with facial differences lack content validity, as few items address appearance and function issues. The FACE-Q is a new PROM developed to measure outcomes important to patients aged 8-29 years with craniofacial conditions. A process was needed to determine if the FACE-Q content is relevant to patients with head and neck cancer (HNC). Methods: Cognitive interviews with patients with HNC aged 8 to 29 years (n=15) were conducted and feedback from experts in pediatric oncology (n=21) was obtained. Input was sought on all aspects of the FACE-Q content. Results: A total of 1573 codes were developed from patient comments and 234 codes were developed from expert feedback that related to the COSMIN criteria for judging content validity. A total of 12 items were flagged for review from qualitative interviews and 4 comments were coded from expert feedback among the core scales for comprehensibility. Instructions, time frame, and response options were found to be comprehensible and appropriate by almost all patient and expert participants. Participants identified a total of 10 missing items identified across the core scales, while no additional items were identified by experts for the core scales. However, 4 experts identified swallowing/dysphagia as an important item missing from the mouth function scale. Discussion: Content validity of the FACE-Q for patients with HNC was evaluated through cognitive interviews with patients and feedback from pediatric oncology experts. The core scales were answered by all participants and demonstrate overall content validity from feedback offered by both patients and experts. Conclusion: The FACE-Q showed evidence of content validity for its core scales along with limited evidence that the remaining scales covered issues relevant to specific HNC patients. Assessment of the psychometric properties of the new measure is forthcoming as part of an international FACE-Q field-test study. / Thesis / Master of Science (MSc) / The FACE-Q is a patient-reported outcome measure developed to assess outcomes important to patients aged 8-29 years with craniofacial conditions. The current study aimed to determine its content validity for use in patients with head and neck cancer (HNC). Cognitive interviews with patients with HNC aged 8-29 years (n=15) were conducted and feedback from experts in pediatric oncology (n=21) was obtained. A total of 1573 codes from patient comments and 234 codes from expert feedback were developed. A total of 12 items were flagged for review from qualitative interviews along with 4 items from expert feedback among the core scales for comprehensibility. Instructions and response options were found to be comprehensible and appropriate. A total of 10 missing items were identified across the core scales by patient participants while experts identified 1 missing item. The FACE-Q evidenced content validity for core scales along with limited evidence for remaining scales.