The treatment phase of this double-blind study will last a minimum of 32 weeks and will consist of 3 phases. In Phase I, participants will be randomly assigned to receive either rTMS or sham stimulation. The sham stimulation will mimic the sensation of rTMS but will not induce an intracerebral current. Treatments will be administered daily for 3 weeks. Participants who show signs of improvement may continue Phase I for up to 3 additional weeks. In Phase II, participants who were unresponsive to Phase I treatment will receive daily rTMS at a lower dose for 3 weeks. Participants who show signs of improvement, but have not achieved remission, may continue Phase II for 4 additional weeks. Baseline magnetic resonance images will be used to determine the optimal stimulus intensity by adjusting for individual differences in cortical to skull distances. Phase III participants will be only those who achieved remission in the first 2 phases. These participants will receive antidepressant medication treatment daily for six months. Participants' functional status and symptoms of depression will be measured using self-report scales and video-recorded interviews at study start date and at the end of each treatment phase.