Objectives of this study are to determine whether active VNS Therapy treatment is superior to a no stimulation control in producing a reduction in baseline depressive symptom severity, based on multiple depression scale assessment tools at 12 months from randomization.

A prospective, multi-center, randomized, controlled, blinded trial of subjects implanted with VNS Therapy. Active treatment and no stimulation control are randomized, at least two weeks after implantation and observed for 12-months.

After completing the 12 month endpoint in the RCT portion of the study, all RECOVER subjects will transition into the prospective, open-label, longitudinal portion of the study. Subjects in the control arm of RECOVER will be activated after completing the 12 month endpoint.

After completion of enrollment in the RCT portion or meeting of interim success criterion (whichever comes first), up to 5,800 new subjects may enroll directly into the open-label,prospective, longitudinal study. These subjects will participate in the study for approximately 5 years.

The study has been designed in accordance with The Centers for Medicare and Medicaid Services coverage with evidence development (CED) decision entitled "Decision Memo for Vagus Nerve Stimulation (VNS) for Treatment Resistant Depression (TRD) (CAG-00313R2).

Inclusion Criteria:

The patient must be in a major depressive disorder (MDD) episode for ≥ two years or have had at least four episodes of MDD, including the current episode.

The patient's depressive illness meets a minimum criterion of four prior failed treatments of adequate dose and duration as measured by a tool designed for this purpose.

The patient is experiencing a major depressive episode (MDE) as measured by a guideline recommended depression scale assessment tool on two visits, within a 45-day span prior to implantation of the VNS device.

Patients must maintain a stable medication regimen for at least four weeks before device implantation.

Exclusion Criteria:

Current or lifetime history of psychotic features in any MDE;

Current or lifetime history of schizophrenia or schizoaffective disorder;

Current or lifetime history of any other psychotic disorder;

Current or lifetime history of rapid cycling bipolar disorder;

Current secondary diagnosis of delirium, dementia, amnesia, or other cognitive disorder;

Current suicidal intent; or

Treatment with another investigational device or investigational drugs.

Central Rater and sponsor are blinded in the RCT phase. Sites will need to have an unblinded programmer who is only programming the device and not collecting outcomes data.