Pilot Study Comparing 10hz vs Theta Burst Stimulation

Inclusion Criteria: * outpatients * voluntary and competent to consent * Mini-International Neuropsychiatric Interview (MINI) confirmed diagnosis of Major Depressive Disorder (MDD), single, recurrent between ages 18-65 * failed to achieve a clinical response to an adequate dose of an antidepressant based on an Antidepressant Treatment History Form (ATHF) score of ≥ 3 in the current episode or have been unable to tolerate at least 2 separate trials of antidepressants of inadequate dose and duration (ATHF 1 or 2) * have a score of ≥ 18 on the Hamilton Depression Rating Score 17-item (HDRS-17) * have had no increase or initiation of any psychotropic medication in the 4 weeks prior to screening able to adhere to the treatment schedule * Pass the TMS adult safety screening (TASS) questionnaire * have normal thyroid functioning based on pre-study blood work Exclusion Criteria: * have a history of substance dependence or abuse within the last 3 months * have a concomitant major unstable medical illness, cardiac pacemaker or implanted medication pump * have active suicidal intent * are pregnant * have a lifetime MINI diagnosis of bipolar I or II disorder, schizophrenia, schizoaffective disorder, schizophreniform, delusional disorder, or current psychotic symptoms * have a MINI diagnosis of obsessive-compulsive disorder, post-traumatic stress disorder (current or within the last year), anxiety disorder (generalized anxiety disorder, social anxiety disorder, panic disorder), or dysthymia assessed by a study investigator to be primary and causing greater impairment than MDD