Workplace violence prevention legislation came into effect in Ontario in 2010. The legislation amended the Occupational Health and Safety Act to direct employers to: establish violence prevention policies that are reviewed annually; develop and maintain a program for controlling risks, summoning assistance, and reporting and responding to incidents; assess risks of workplace violence; and train and educate employees. This report details the findings of an Institute for Work & Health study that looked at how five acute-care hospitals in Ontario implemented the violence prevention legislation, to what effect, and the challenges they faced along the way.