Inclusion Criteria:

• Male or female, 6 years or older at baseline visit (Canada has received the country's regulatory approval for use of Dupixent treating msAD for these ages).
• Participant is initiating dupilumab as part of routine clinical care through the Dupixent Patient Support Program (PSP) for the treatment of msAD, as per reimbursement criteria. Decision to treat with dupilumab must have been reached prior to and independently of recruitment in the study.
• Have a physician's diagnosis of msAD.
• Provided signed informed consent or parental/legally acceptable representative consent and/or participant assent. During the study, subjects will continue to receive maintenance therapies for their AD as clinically indicated and as per usual medical practice.
• Participant or Parental representative able to understand English and/or Canadian French to complete study-related questionnaires.

Exclusion Criteria:

• Participants who have a contraindication to the drug according to the Canadian-specific prescribing information label.
• Any condition that, in the opinion of the Investigator, may interfere with participant's ability to participate in the study, such as short life expectancy, substance abuse, severe cognitive impairment, or other comorbidities that can predictably prevent the participant from adequately completing the schedule of visits and assessments.
• Participants currently participating in any interventional clinical trial which modifies participant care.
• Prior use of Dupixent within 6 months of the baseline visit.
• Participants not willing to sign the Informed Consent Form.