BACKGROUND Behavioral activation system (BAS) deficits are hypothesized to increase risk for depression. This study tested the hypothesis that BAS deficits, measured with both self-report and electrophysiological methods, would predict the six-month course of depression. METHODS 67 participants with major depressive disorder (MDD) with or without pre-existing dysthymia were assessed at baseline with Carver and White's [Carver, C.S., White, T.L., 1994. Behavioral inhibition, behavioral activation, and affective responses to impending reward and punishment: the BIS/BAS scales. J. Pers. Soc. Psychol. 67, 319-333.] BIS/BAS scales and resting EEG. The week-by-week course of their depressive symptoms was assessed six months later with the Longitudinal Interval Follow-up Evaluation (LIFE). RESULTS Baseline self-reported BAS sensitivity predicted depression diagnosis (MDD or dysthymia) at follow-up, number of MDD symptoms at follow-up, average weekly level of depression, and time to recovery. These effects persisted after controlling for baseline clinical variables associated with a worse course. Baseline resting EEG alpha asymmetry did not significantly predict the course of depression. CONCLUSIONS Although BAS sensitivity predicted the subsequent course of depression, we cannot determine whether it played a causal role in maintaining depression. CONCLUSIONS Lower self-reported BAS sensitivity predicts a worse course of depression but EEG asymmetries do not.