This is a double-blind placebo controlled study to assess the CRF1 receptor antagonist, GSK561679, for treatment of depression in adult females diagnosed with Major Depressive Disorder (MDD). A treatment regimen of 350mg/day will be utilized to assess both efficacy and tolerability. Subjects will be randomized in equal numbers (n=75/arm) to the treatment arm and the placebo arm for a 6-week treatment period.