According to the Chicago Crime Commission (CCC), 729 people were slain gangland style in Cook County, IL during the Prohibition Era from 1919 to 1933. Using the CCC records, Chicago Police Department (CPD) homicide records (2012), and newspaper accounts, this study analyzed a variety of data about these killings, including the types of killings as well as the major reasons for the killings, such as bootlegging, gambling, labor racketeering, vice, or other criminal disputes. Many of the study's results contradicted conventional wisdom. For example, 43 percent of the killings were unrelated to organized crime. Also, only 40 percent of the killings were tied to bootlegging, and the victim belonged to one of the major bootlegging gangs in the area in only 40 percent of those cases. Therefore, while various members of Chicago's Prohibition Era gangs were killed, those casualties are much smaller than expected. Abstract published by arrangement with Sage Journals.