A Clinical Study That Will Measure How Well SEP-363856 Works and How Safe it is in Adults With Generalized Anxiety Disorder

Inclusion Criteria: (list is not all inclusive)

• Male or female subject between 18 to 65 years of age.

• Subject meets DSM-5 criteria for a diagnosis of Generalized Anxiety Disorder.

• Subject must be willing and able to comply with the study procedures and visitschedule and must be able to understand and follow verbal and written instructions.

Exclusion Criteria: (list is not all inclusive)

• Subject has DSM-5-based diagnosis of any disorder other than Generalized AnxietyDisorder that was the primary focus of treatment within 12 months before Screening.

• Subjects who report an inadequate response to more than 3 antidepressant treatments

• Subject is at significant risk of harming self or others based on Investigator'sjudgment.

• Subject has any clinically significant unstable medical condition or any clinicallysignificant chronic disease that in the opinion of the Investigator, would limit thesubject's ability to complete and/or participate in the study.

• Female subject who is pregnant, lactating, or plans to get pregnant during thestudy.