The Bandaranaike–Chelvanayakam Pact was an agreement signed between the Prime Minister of Sri Lanka S. W. R. D. Bandaranaike and the leader of the main Tamil political party in Sri Lanka S. J. V. Chelvanayakam on July 26, 1957. It advocated the creation of a series of regional councils in Sri Lanka as a means to giving a certain level of autonomy to the Tamil people of the country, and was intended to solve the communal disagreements that were occurring in the country at the time.
The act was strongly opposed by certain sections of both the Sinhalese and Tamil communities, and was eventually torn up by Prime Minister Bandaranaike in May 1958. The abandonment of the pact led to tensions between the two communities, resulting in a series of outbreaks of ethnic violence in the country which eventually spiraled into the 26 year Sri Lankan Civil War. Prime Minister Bandaranaike's later attempts to pass legislation similar to the agreement was met by strong opposition, and led to his assassination by a Buddhist monk in 1959.
Following the gaining of independence for Sri Lanka from Britain in 1948, English continued to be the official language of the country. However sections within the Sinhalese community, who wanted the country to distance itself from its colonial past, began a campaign to have Sinhala made the official language of Sri Lanka. At the 1956 parliamentary elections, the leader of the Mahajana Eksath Peramuna, S. W. R. D. Bandaranaike campaigned on a promise to make Sinhala the sole official language of Sri Lanka. With the support of extremist Sinhalese figures, Bandaranaike won the election and was named the 4th Prime Minister of Sri Lanka. After his government was set up, he made it his priority to follow up on his promises related to the language issue, and introduced the Official Language Act (commonly known as the Sinhala Only Act) on June 5, 1956. In opposition to the act, Tamil People staged a hartal in parts of the country, and demonstrated in front of the parliament at Galle Face Green.