Depression has been declared by the World Health Organization in March of 2017 to be the illness with the greatest burden of disease in the world. This volume attempts to examine the current state of our understanding of depressive disorders, from the animal models, allostatie load, patterns of recurrence, effects on other illnesses, for example, cancer, neurological, cardiovascular, wound healing, etc. It is from this perspective that the editors declare that depression is a systemic illness, not just a mental disorder. Therefore, primary care physicians need to know how to diagnose, treat, and refer when necessary for the non-complicated, non-refractory forms of depression. From this perspective models of mental health training for the primary care physician are reviewed. Then a new model, the medical model, a step beyond collaborative care is described. Non complicated depressive illness needs to be addressed by the primary care physician much as they do asthma, diabetes, hyptertension, and congestive heart failure. Even collaborative care models are unable as the number of psychiatrists is too few even in developed countries, let alone in developing ones to work with primary care. Medical schools and residency training programs need to incorporate curriculum and clinical experiences to accommodate developing expertise to diagnose, treat, and refer when necessary in this most common medical malady. Finally, a modified electronic medical record is proposed as a collaborating agent for the primary care physician.