Frontal cortex activity in the left hemisphere during depression is reduced. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that can increase frontal cortex activity. Therapy based on tDCS and positive psychology (PP) therapy was applied improving patients' quality of life. The present study compared three conditions participants with clinical depression; (a) tDCS therapy, (b) positive psychotherapy, and (c) combined treatment. Hamilton Depression Rating Scale (HDRS), Adult State Hope Scale and Optimism/Pessimism Scale (OPS) was used at baseline, 2 weeks, 4-weeks and 3-months follow-up. Combined condition participants showed greater reduction in depressed mood, improved hope and optimism after 4-weeks as well as during 3-months follow-up than the other conditions. The results are discussed in terms of additive or synergistic relation between tDCS and PP treatment. Future studies should (a) use larger sample-sizes, (b) include no-treatment control conditions, (c) include double-blind designs, (d) control for previous or on-going drug therapy, (d) control for previous or ongoing psychotherapy. Furthermore, future studies should aim to increase theoretical understanding by investigating whether the relation between tDCS and psychotherapy are additive or synergistic.