Objective: To evaluate remission and recovery, safety, and tolerability for up to 12 months of open-label adjunctive l-methylfolate calcium 15 mg. Method: Subjects in this analysis were adult outpatients (18-65 years) enrolled from 2 acute, double-blind, placebo-controlled trials comparing adjunctive l-methylfolate and placebo for DSMIV major depressive disorder (MDD) with an inadequate response to monotherapy selective serotonin reuptake inhibitor (SSRI). Subjects who completed the acute trial were offered to enroll in a 12-month, open-label treatment phase with l-methylfolate and continued SSRI treatment, with scheduled visits for efficacy, safety, and tolerability every 12 weeks. Subjects were enrolled between September 2006 and February 2010. Efficacy outcomes included predefined criteria for response, remission, recovery, relapse, and recurrence. Subjects treated with adjunctive l-methylfolate 15 mg were included in the efficacy analysis. Results: Of 68 subjects who met criteria for the 12-month open-label phase, 38% (n = 26) achieved full recovery, and none experienced a recurrence of MDD. For subjects entering the open-label phase in remission (n = 11), 91% (n = 10) achieved full recovery with l-methylfolate 15 mg, and none experienced a relapse or recurrence. Among 57 subjects who entered the openlabel phase as nonremitted, 61% (n = 35) achieved remission. Of subjects who entered the open-label phase with a response without remission (n = 4), 50% (n = 2) had full recovery, and of subjects entering the open-label phase with no response (n = 53), 26% (n = 14) met recovery criteria. Conclusions: Adjunctive l-methylfolate 15 mg/d may be an early option in patients who fail to adequately respond to antidepressant monotherapy, with preliminary evidence demonstrating sustained remission and sustained recovery.