Chapter 9 examines the long-standing hypothesis that psychopathology plays a role in creative thinking – genius and madness. Modern opinions on the relationship between creativity and psychopathology vary widely, ranging from the idea that psychopathology influences creativity, to the complete opposite – that there is no relation between genius and madness. This chapter examines the complexities involved in trying to determine if there is a relationship between genius and madness. It begins with a discussion of how one might try to test the hypothesis that psychopathology facilitates creativity. We then review the literature on genius and madness; specifically, the possible relationship between creativity and two disorders, bipolar disorder (manic-depressive disorder) and schizophrenia. Many researchers have concluded that mild forms of psychopathology, rather than full-blown disorder, may be related to creativity. We examine the evidence for that conclusion. The discussion places the study of genius and madness in the broader social context and examines the many factors that play a role in determining whether or not psychopathology and creativity are related.