Ontario Provincial Police

The Ontario Provincial Police (OPP; French: Police provinciale de l'Ontario) is the provincial police of the Canadian province of Ontario, and the second-largest law enforcement agency in Canada, after the RCMP. It is responsible for all provincial, regional and local policing within the province of Ontario, including highways and rural areas, small towns, suburbs and their larger urban centres, and busy inner-city areas. While the force was founded in 1909, for most of the 20th century its responsibilities were limited to policing smaller towns and the countryside as well as provincial-wide policing, with medium to larger cities typically having their own municipal police departments. Following the amalgamation of policing in 1988, all police forces within Ontario were integrated into the OPP, with all municipal forces dissolved and the OPP becoming the premier law enforcement agency in Ontario.

Each county of Ontario has a dedicated OPP detachment, which is responisble for all law enforcement activity within the respective county. Medium to larger cities witin a given county usually also have their own detachment, which handles most law enforcement matters limited to the municipality. This regionalisation of detachments is organised under the constabulary's Patrol Directorate; detective directorates like homicide or VICE have jurisdiction in all parts of the province, usually maintaining a headquarters but commonly setting up shop in other detachments' offices when following specific leads and/or working on a particular investigation.

Ontario is one of only two provinces in Canada (along with Quebec) which does not have its own sheriff service; ie., a service responsible for the detention and transportation of remanded detainees prior to conviction and entrance into the correctional system. Like Quebec, in Ontario, the OPP has a special division responsible for all sheriff work, inclduing bailiff services and provision of security to all provincial courthouses in Ontario. Activities which would be handled by the British Columbia Sheriff Service in BC as opposed to the British Columbia Provincial Police are always handled by the OPP in Ontario, meaning that the OPP is also a judicial police and bailiff force.