At the wheels of railroads and streetcars, the law of accidental personal injury, known as negligence, became a discrete body of law between 1870 and 1920. The defining component of negligence was “fault”–the notion that the individuals (injured and injurer) must have failed to act according to some minimal standard of caution. Theorists of the history of negligence have explained that the conduct of all was measured against what a “reasonable man” would have done under the circumstances. The author here challenges this fundamental assertion. Through trial records, lawyer's written arguments, and appellate opinions, she reconstructs the critical role of gender in shaping the law of accidental injury. As she argues, in 19th- and 20th-century America, injury was a gendered event. The fact that courts in these years held men and women to different standards of care undermines theorists' arguments that economic considerations drove the law of accidental injury. Moreover, the reification of gender nm in private law, in turn, vitally affected the experience of gender in turn-of-the-century America.