Canadian Avonex PEN Productivity Study

Key Inclusion Criteria: * Must be prescribed AVONEX PEN as per local labeling (Product Monograph) and enrolled in MS Alliance (MSA) program * If being switched from another DMT, must be on this DMT for at least 6 months * Last DMT the subject is switched from must be injectable * Must be able to physically demonstrate use of the AVONEX PEN autoinjector device and be able to self-administer the injections * Must give written informed consent. If required by local law, candidates must also authorize the release and use of protected health information (PHI) * Must be able to understand and comply with the protocol Key Exclusion Criteria: * Female subjects considering becoming pregnant while in the study or who are currently pregnant or breast-feeding * Current enrollment in any investigational study involving drug, biologic or non-drug therapy * Participation in other clinical studies within the past 6 months * Treatment with immunosuppressive regimens (e.g. cyclophosphamide, azathioprine, methotrexate or mitoxantrone) or with intravenous immunoglobulin (IVIg) in the last 6 months * The most recent DMT the subject is switched from is non-injectable (i.e., oral) * Other unspecified reasons that, in the opinion of the Investigator or Sponsor, make the subject unsuitable for enrollment NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.