Inclusion Criteria:  Has a diagnosis of NMOSD at the time of enrollment according to the 2015 IPND consensus diagnostic criteria for NMOSD†. Age 18 years or older at the time of enrollment. Willing to provide Personal Information.  Exclusion Criteria:  Has had a clinically confirmed NMOSD neuro-episode within the 12 weeks prior to enrollment.  Is participating or planning to participate in a double-blind randomized trial for an NMOSD drug. Note: Concurrent participation in another observational registry or open-label Phase 3b/4 trial is allowed.  All serology types (APQ4 +/- and MOG +/-) are eligible to enroll in the registry given they meet the 2015 IPND diagnostic criteria.