It is commonly believed that the lack of social support is a cause of neurotic depression. The hypotheses to be tested are that this effect holds either independently or only in the presence of adversity. In cross-sectional studies, the expected association has repeatedly been demonstrated. But this means little for etiology, because of important reasons in the interpretation. A recent prospective longitudinal study has produced evidence for the overriding dominance of constitutional or personality attributes. In the face of adversity, these are much more powerful than the lack of supportive social relationships. Vulnerability to depression is more likely to reside within the individual than within his social environment.