Many patients with Major Depressive Disorder (MDD) and generalized Social Anxiety Disorder (gSAD) are treated with cognitive behavioral therapy (CBT) but few have meaningful improvement. MDD and gSAD are diseases of brain dysfunction that manifest as impaired emotion regulation; CBT teaches emotion regulation strategies but how it works in the brain remains largely unknown. Individual differences in brain function related to emotion regulation may make some patients better suited for CBT and CBT may remedy the brain dysfunction that underlies these disorders. This project will compare CBT with a placebo psychotherapy (i.e., supportive therapy) in MDD and gSAD to test, validate, and refine brain-based markers and examine mechanisms of change to examine how CBT works and for whom.