The concept of personality disorders rose to prominence in the early twentieth century and has consistently caused controversy among psychiatrists, psychologists, and social scientists. In Personality Disorders, Allan V. Horwitz traces the evolution of defining these disorders and the historical dilemmas of attempting to mold them into traditional medical conceptions of disorder.

Using the Diagnostic and Statistical Manual of Mental Disorders, or DSM, as a guide, Horwitz explores the group of conditions that make up personality disorders and considers when they have been tied to or separated from other types of mental illnesses. He also examines how these disorders have often entailed negative moral and cultural evaluations more focused on perceived social deviance than on actual medical conditions.

Deep conflicts exist in a variety of disciplines in determining the nature of these disorders. During the twentieth century, a particularly sharp division arose between researchers who study personality disorders and the clinicians who treat them. Because researchers strive to develop general laws and clinicians attempt to understand individuals' specific problems, their values, methods, and goals often conflict. Synthesizing historical and contemporary scholarship, Horwitz examines controversies over the definitions and diagnoses of personality disorders and how the perception of these illnesses has changed over time.