Inclusion Criteria:  are female or male; are outpatients; are voluntary and competent to consent to treatment; have a DSM 5 diagnosis of MDD,55 single or recurrent confirmed by Mini-International Neuropsychiatric Interview (MINI) version 7.0; are 18yo to 65yo; have 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 two separate trials of antidepressants at less than the minimum adequate dose and/or duration (ATHF 1 or 2); have a score ≥ 18 on the Hamilton Depression Rating Scale (HDRS-17 item); have had no increase or initiation of any psychotropic medication in the 4 weeks prior to screening; are able to adhere to the treatment schedule; pass the TMS and MRI adult safety screening questionnaires.  Exclusion Criteria:  have a history of substance use within the last 3 months; have a concomitant major unstable medical illness; have active suicidal intent; are pregnant; have a lifetime (MINI) diagnosis of any psychotic or bipolar disorder; have a MINI anxiety disorder or personality disorder assessed by a study investigator to be primary and causing greater impairment than MDD; have failed a course of ECT in the current episode; have any significant neurological disorder, any history of seizure (except those therapeutically induced by ECT), significant head trauma with loss of consciousness for > 5 min; have any intracranial implant (e.g., aneurysm clips) or any other metal object within or near the head, excluding the mouth, that cannot be safely removed; are participating in psychotherapy, must have been in stable treatment for at least 3 months prior to study entry, with no anticipated change in the frequency of therapeutic sessions, or focus of therapeutic sessions over the duration of the study; have a clinically significant laboratory abnormality, in the opinion of the one of the principal investigators; have a non-correctable clinically significant sensory impairment (i.e., cannot hear well enough to cooperate with interview);