Psychiatric disorders are one of the most dramatic burdens for humankind. The role of immune dysfunction in the pathophysiology of these disorders has emerged during the last years, because there has been tremendous progress in psychoneuroimmunological research. Many results are presented here by pioneers in the field. The book addresses various effects of the immune system on the pathophysiology and course of psychiatric disorders and highlights the possible future impact on treatment decisions of various psychiatric disorders, including schizophrenia and depression. The contributions cover the role of in utero immune challenges on the development of schizophrenia, the role of infections, and autoimmune diseases and mild immune activation in the development of depression and schizophrenia, the influence of immune responses in other disorders such as Tourette’s, Alzheimer’s, and OCD, the connections between mental and physical pain as well as between anti-inflammatory and antipsychotic drugs.