Abusive head trauma (AHT) is a severe form of child abuse causing devastating outcomes for children and families, but its economic costs in Canada has yet to be determined. The Period of PURPLE crying program (PURPLE) is an AHT prevention program implemented in British Columbia for which success in reducing AHT events was recently reported.This study estimated the lifetime costs to society of incidental AHT events and compared the benefits and associated costs of AHT before and after the implementation of the PURPLE program.Children aged 0-24 months old with a definite diagnosis of AHT between 2002 and 2014 in British Columbia were included in this study.An incidence-based cost-of-illness analysis, using the human capital approach was used to quantify the lifetime costs of AHT events according to their severity (least severe, severe and fatal). A cost-effectiveness analysis of the PURPLE program was conducted from both a societal and a health services' perspectives using decision tree models.There were sixty-four AHT events between 2002-2014, resulting in a total cost of $354,359,080 to society. The costs associated with fatal, severe and least severe AHT averaged $7,147,548, $6,057,761 and $1,675,099, respectively. The investment of $5 per newborn through the PURPLE program resulted in a $273.52 and $14.49 per child cost avoidance by society and by the healthcare system.This study provides evidence to policymakers and health practitioners that investing upstream in well-developed AHT prevention programs, such as PURPLE, not only promote child safety and health, but also translates into avoided costs to society.