For the initial phase of treatment, subjects will be randomly assigned to treatment with an SSRI, (escitalopram oxalate or citalopram hydrobromide), or with interpersonal psychotherapy (IPT). Escitalopram will be prescribed for all patients randomized to the medication arm of the study, unless the study psychiatrist determines that citalopram is more clinically appropriate. Escitalopram and citalopram are FDA-Approved SSRI antidepressants indicated for the treatment of depression. In order to optimize outcomes and emulate usual clinical practice, subjects who do not meet response criteria (defined as a 50% reduction in baseline Hamilton Rating Scale for Depression [HRS-D]) or meet stabilization criteria (defined as a mean HRS-D < 7 for 3 weeks) at acute phase Visit 7 or Visit 13 of treatment will have the other treatment added. Subjects who meet stabilization criteria (mean HRS-D < 7 for 3 weeks) at any time between acute phase Visit 13 and 21 will enter the 6-month continuation phase and continue with the treatment that led to their stabilization. Subjects who have not met stabilization criteria by acute phase Visit 21 will remain in active treatment and be offered alternative pharmacotherapy. Subjects who have not responded by acute phase Visit 32 will be discontinued from the protocol and referred for alternative treatment and care.