In recent years, a dedicated effort has been made to understand the immune dysfunction that is associated with major psychiatric disorders. The expanding knowledge of the immune system as a major homeostatic system has been very helpful in indicating new potential biomarkers and therapeutic targets to reduce the burden of psychiatric disorders. Indeed, immune cells, their secreted molecules, and cell signalling events are highly promising. Yet, the literature on immunology of psychiatric disorders is still dispersed, and only a few attempts have been made to consolidate the current knowledge in this expanding area. This book assembles and presents the available data on the immune/inflammatory dysfunction in psychiatric disorders, indicating the potential of immune mechanisms as either biomarkers or therapeutic targets, as well as discussing the challenges ahead of incorporating this knowledge into clinical practice. An international team of senior experts in the field review all psychiatric disorders in order to provide an integrated, in-depth understanding of the role of immune changes in psychiatric diseases for mental health clinicians as well as for researchers in immunology, psychiatry, neurology, and pharmacology.