Objective: This randomized controlled trial (RCT), conducted in patients with breast cancer, aimed to compare the effects of cognitive therapy (CT), bright light therapy (BLT), and a waiting-list control condition (WLC) on depressive symptoms. Method: Sixty-two women were randomly assigned to an 8-week CT (n = 25), BLT (n = 26), or WLC (n = 11). Participants completed the depression subscale of the Hospital Anxiety and Depression Scale (HADS-D), the Beck Depression Inventory-II (BDI-II), and the Hamilton Depression Rating Scale (HDRS) at pre- and posttreatment (and postwaiting for WLC), as well as 3 and 6 months later. Results: At posttreatment, CT patients had a significantly greater reduction of depressive symptoms than WLC on the HADS-D and the BDI-II. BLT patients had a greater reduction of depressive symptoms than WLC on the HADS-D only. After WLC participants were reassigned to CT or BLT, a superiority of CT over BLT was found on the BDI-II at posttreatment. Patients of both active conditions showed a good sustainment of treatment gains at follow-ups. Conclusions: Although replication with larger samples is needed, these results confirm the efficacy of CT for depression in the context of breast cancer and suggest that BLT could be of some utility when CT is not available or desired.