It is at 31.4 years of age that the average woman multiple murderer kills the first of her 17 victims, whom she usually knows or is related to. The preferred method is poison, usually arsenic. She is more likely to prey on the vulnerable—the very young or the very old—than is her male counterpart. Her killing spree lasts five years; when caught, she shows little remorse. This study of 85 women focuses on those who have killed at least three people, not including themselves in murder-suicide cases. Though the work is international, emphasis is on the United States during the late 19th and 20th centuries. Excluded are accomplices who, though legally guilty of multiple murders, were in fact passive participants. The life of each killer is examined, as well as descriptions of the murders, the methods, and the trial.