Segregation in Northern Ireland is a long-running issue in the political and social history of Northern Ireland. The segregation involves Northern Ireland's two main voting blocs—Irish nationalist/republicans and British unionist/loyalist. It is often seen as both a cause and effect of the "Troubles".

The Troubles were an ethno-nationalist conflict in Northern Ireland that lasted for about 30 years from the late 1960s to 1998. Also known internationally as the Northern Ireland conflict, it is sometimes described as an "irregular war" or "low-level war". The conflict began in the late 1960s and is usually deemed to have ended with the Good Friday Agreement of 1998. Although the Troubles mostly took place in Northern Ireland, at times violence spilled over into parts of the Republic of Ireland, England, and mainland Europe.