As Schiavi pointed out in the previous edition of this book, “emphasis on specific determinants of erectile disorders has been influenced by prevailing theoretical perspectives as they have shifted over the time”. We have certainly seen a shift from the emphasis on psychological causes or determinants of erectile dysfunction to an emphasis on biological or organic causes of erectile dysfunction. The previous claims that 90%-100% of erectile dysfunctions have psychological origins changed to claims that 90%-100% of erectile dysfunctions have biological or organic causes. However, every experienced clinician in this area knows that the etiology of erectile dysfunction is usually multidetermined, involving a mixture of organic and psychological factors. Even an unequivocally biologically determined erectile dysfunction, such as erectile dysfunction associated with diabetes mellitus, has a psychological component.