In this article the authors analyze a century of research on the causes and consequences of wrongful convictions in the American criminal justice system while explaining the many lessons of this body of work. This article chronicles the range of research that has been conducted on wrongful convictions; examines the common sources of error in the criminal justice system and their effects; suggests where additional research and attention are needed; and discusses methodological strategies for improving the quality of research on wrongful convictions. The authors argue that traditional sources of error (eyewitness misidentification, false confessions, perjured testimony, forensic error, tunnel vision, prosecutorial misconduct, ineffective assistance of counsel, etc.) are contributing sources, not exclusive causes, of wrongful conviction. They also argue that the research on wrongful convictions during the last hundred years has uncovered a great deal about how these sources operate and what might prevent their effects. Finally, the authors urge criminal justice professionals and policy-makers to take this research more seriously and apply the lessons learned from a century of research into wrongful convictions.