From the abundance of psychoanalytic theories of depression the author establishes five characteristic types of depression on the basis of the cardinal symptom represented by the nature of the feelings prevalent in each case. Will makes no claim to advancing a unified theory but draws upon existing theoretical concepts to describe the following types of depression: super-ego depression; oral-dependent depression; ego depression; narcissistic depression; realistic-creative depression. There is also an initial brief discussion of the general characteristics of depression.