Depression is a most widely researched psychopathology, both psychologically andphysiologically. The best known psychological theories focus on maladaptive cognitive responses, which are largely surface manifestations of depression. The cognitive orientation theory (Kreitler Kreitler) can amplify them by providing an assessment of depression based on deeper insights into the underlying dynamics of depression.

To test the validity of the Cognitive Orientation Questionnaire of Depression (CO-D).

To test hypotheses that the CO-D differentiates between high and low scorers on twomeasures of depression, between women high and low on postnatal depression, andindividuals diagnosed with depression and other patients.

The CO-D was administered to 50 undergraduates who also responded to the Beck Depression Inventory and the Goldberg Depression Questionnaire, 100 women who gave recently birth and responded also to the Edinburgh Postnatal Depression Scale,and 25 patients in a psychiatric clinic 13 of whom were diagnosed with depression. The CO-D items represented four belief types (about self, reality, norms and goals) referring to themes identified as relevant in pretests, e.g., harm avoidance, perfectionism, responsibility.

The scores of the CO-D differentiated significantly between the high and low scorers on depression in the Beck, Goldberg and Edinburgh scales and in the psychiatric group. All four belief types had significant contributions. The major significant themes were responsibility and guilt.

The CO-D is a valid tool that may be used for the assessment and treatment of depression, and for constructing a broader theoretical approach to depression.