Major depression is a leading cause of disease burden worldwide. Although various treatment approaches exist, including pharmacological (eg, antidepressant agents), psychotherapeutic (eg, cognitive-behavioral therapy), and neuromodulatory (eg, electroconvulsive therapy [ECT]), a substantial number of patients do not adequately benefit from or cannot tolerate these existing options. This has led to a re-emergence of other neurostimulation strategies, the best studied to date being transcranial magnetic stimulation (TMS). This article reviews the rationale for TMS in treating depression with a brief description of the basic principles underlying magnetic stimulation; a discussion of its putative mechanism of action; and its recommended treatment parameters. We then focus on the evidence base to support its use as both a monotherapy and adjunctive therapy for the acute and maintenance treatment of major depression. These data came from controlled trials comparing TMS to a sham procedure and naturalistic outcome studies for acute depression; studies directly comparing TMS to ECT for major depression; and open-label studies, retrospective analyses, naturalistic outcome studies, and case reports that consider the durability of TMS’ effect after acute response. The results of these studies have led to a growing use of TMS in clinical practice for treatment-resistant depression. [ Psychiatr Ann . 2014; 44(6):284–292.]