The design will be a randomized, double blind study with patients being randomized to switching to either vilazodone or sertraline. This will consist of a 1-week Screening phase, a 2-week Cross Taper phase, an 8-week Treatment phase, and an optional 2-week Down taper phase. The total duration of each patient's participation will be 13 weeks.
Seventy-two patients will be randomized at the Baseline visit to either vilazodone or sertraline, 24 at each of the 3 sites. Patients will be recruited over 12 months.
