Cognitive therapy alone without concurrent behavioral components seems to be ineffective in the treatment of depressive patients. However, the combination of cognitive and behavioral treatment procedures including social skills training is effective even in the therapy of definite endogenous depression. Three important characteristics are mentioned explaining the therapeutical effectiveness: a concrete rationale, a highly structured therapy program and feedback- and support-techniques. Effectiveness and outcome of the various treatment methods are discussed in the light of three aetiological cognitive hypotheses: the Precipitation theory, the Vulnerability theory and the ‘depression about depression’ hypothesis.