While western countries have had a decentralized policing model for many years, some countries, such as South Korea, still employ a centralized, national police department. Responding to calls for reform, South Korea launched a pilot program and implemented a more decentralized policing structure in Jeju Island in 2006. This study adds to the policing literature by offering the empirical comparison of a region before and after decentralization of a police department. This study will examine the intervention effects of police decentralization in Jeju, specifically related to crime rates, crime clearance rates, victimization, trust in police, and fear of crime. Using propensity score matching and interrupted time series analysis, this study found that the decentralized policing intervention significantly reduced total crime, violent crime rates, and property crime rates that lasted throughout the intervention period, while improving crime clearance rates for violent crime, as well as reduced fear of crime among residents.