Although monotherapy is generally recommended as the treatment of choice, treatment resistance in patients with psychosis, cognitive, mood, and anxiety disorders represents a significant clinical problem. In this context, augmentation and combination strategies are commonly employed to address this issue. Although multiple medication use is common in psychiatric practice, the reasons, efficacy, and safety of polypharmacy and augmentative strategies have remained unclear. It is uncertain if there is an evidence base to support polypharmacy. Furthermore, excessive and inappropriate use of psychotropic medications has been recognized as a public health problem. This volume set is the first comprehensive, clinically oriented reference on the use of multiple medications to treat psychotic, cognitive, mood, and anxiety disorders.