Eligibility Criteria:
Inclusion Criteria:
* Diagnosis of Major Depressive Disorder (MDD)
* A CDRS-R score of \>40
* Experiencing a current MDD episode with a duration of ≥ 4 weeks and ≤3 years
* Resistance to treatment, defined by failure to respond adequately to at least one antidepressant treatment, defined by ATR level 1-4 in current episode
* Both child and parent/guardian are English speaking
* Female participants who are sexually active during the course of the study must use a form of birth control for the duration of the study
Exclusion Criteria:
* Any subject with a clinically defined neurological disorder or insult including, but not limited to, a condition likely to increase the risk of seizure; such as, space occupying brain lesion; any history of seizure; history of cerebrovascular accident; transient ischemic attack within two years; cerebral aneurysm; dementia; brain surgery; history or stroke or family history of epilepsy
* Any subject with an increased risk of seizure for any reason, including prior diagnosis of increased intracranial pressure or history of significant head trauma with loss of consciousness for ≥ 5 minutes
* Positive responses to any question on the Transcranial Magnetic Stimulation Adult Safety Screening Questionnaire (TASS)
* Subjects with cardiac pacemakers, implanted medication pumps, intracardiac lines, or acute unstable cardiac diseases
* Subjects with conductive, ferromagnetic, or other magnetic-sensitive metals implanted in the head within 30 cm of the treatment coil excluding the mouth that cannot safely be removed should be excluded. Examples include cochlear implants, implanted electrodes/stimulators, aneurysm clips or coils, stents, bullet fragments, jewelry and hair barrettes
* Subjects with active or inactive implants (including device leads), including deep brain stimulators, cochlear implants, and vagus nerve stimulators
* Inability to locate and quantify a motor threshold as defined in the protocol
* History of treatment with ECT or TMS therapy for any disorders
* Participation in any investigational drug trial within 4 weeks of the baseline visit
* Pregnancy
* IQ \< 80
* Clinically significant laboratory abnormality or medical condition, that in the opinion of the investigator would hinder the subject in completing the procedures required by the study
* Suicide attempt within the previous 6 months that required medical treatment or ≥2 attempts in the past 12 months, or has a clear plan for suicide and states that s/he cannot guarantee that s/he will inform a family member or call his/her psychiatrist or the investigator if the impulse to implement the plan becomes substantial during the study; or, in the investigator's opinion, is likely to attempt suicide within the next 6 months
* Unstable psychotherapy (therapy must be for at least 3 months prior to entry into the study, with no anticipation of change in the frequency or treatment focus of the therapeutic sessions over the duration of the study)
* A diagnosis of substance use disorder, Schizophrenia, Bipolar Disorder, or Autism
* Refusal to cooperate with study procedures
* Recent change in dose of antidepressant medication (within 6 weeks prior to initial evaluation). This includes all antidepressants and any adjunctive psychotropic medications that are being used to address problems related to mood or anxiety (e.g. antipsychotic medications, mood stabilizers.) This does not include stimulant medications that are being used to treat Attention Deficit Hyperactivity Disorder (ADHD).\*\*
* Current treatment with Bupropion at a dose greater than 150mg per day.
* Current treatment with a stimulant medication as an adjunct medication for depression.\*\*\*
* Current treatment with a stimulant medication for ADHD above FDA recommended dosages.\*\*\*
(\*) If the participant has an insufficient number of trials in the current episode, then the participant must also have failed ≥1 and ≤4 trials in a previous episode. Subjects who have been unable to complete an antidepressant trial of adequate dose and duration due to intolerance to antidepressant therapy may be included if they have demonstrated intolerance to ≥4 antidepressant medications within one discrete illness episode (current or previous episode as defined above)
(\*\*) If there has been a recent discontinuation of a medication we will require varying lapses of time before study entry depending on medication type as follows: Antidepressant medications = 4 weeks, mood stabilizers (e.g. Lithium, Valproate) = 2 weeks, Antipsychotic medications = 2 weeks, Stimulant medications = 1 week
(\*\*\*) If participants are being treated with stimulant medications as an adjunct strategy for their depression, we will require them to discontinue the stimulant prior to starting the study treatment and wait 1 week before they begin the study as listed above. If the participant is taking a stimulant medication to treat ADHD, they will be allowed to continue the stimulant medication, as long as the dosage is within FDA recommendations.