First Parish Dorchester is a Unitarian Universalist congregation in Dorchester, Massachusetts. It was founded by English Puritans who initially saw themselves as reformers rather than separatists, but increasingly intolerable conditions in England and at the urging of Reverend John White of Dorchester, Dorset, they emigrated to New England. On March 20, 1630 as they set sail from Plymouth, England on the Mary and John, the congregation wrote its founding church covenant. Nearly all of the 140 ship passengers originated in the West Country counties of Somerset, Dorset and Devon. In late May, the ship landed first at what became called Hull, Massachusetts, and then in June at a place called "Mattapan" by the indigenous people including the Massachusett and Wampanoag. The Puritans named their new home "Dorchester Plantation."

Over time, the congregation's theology changed from its Calvinist Puritan roots to Congregationalism, then Unitarianism around 1816. The American Unitarian Association merged with the Universalist Church of America in 1961, forming the Unitarian Universalist Association and ushering in Unitarian Universalism, a contemporary faith tradition with a long history.

The first church building was a crude log cabin thatched with grass. Beyond the church, the Puritans founded the first elementary school supported by public money in the American colonies. They held the first Town Meeting at the church, also called a Meetinghouse, which determined policy through open and frequent discussion. The congregation's fifth building burned in February 1896, and the current building was completed in 1897.

As of spring 2015, First Parish completed the third of five phases in a $7 million restoration project, which began November 2006. The most recent phase included accessibility improvements, exterior repairs and painting, steeple restoration.

The church played a strong role as the hub of political and social life in Dorchester. The original Puritan congregation is still remembered for establishing the country's first tax-supported, free public school in 1636. In 1641, Dorcas ye blackmore, a servant to Israel Stoughton, was the first recorded African American to join a church in New England, and she taught Stoughton's Native American servants about the gospel message, and the church attempted to help Dorcas gain her freedom. The first four meetinghouses acted as Dorchester’s town hall. The fifth building, built in 1816, was the host to many social justice leaders, such as William Lloyd Garrison and Theodore Parker, because of First Parish's long-standing pastor, the Reverend Nathaniel Hall, who was dedicated to the abolitionist cause. In the 1880s, the work of First Parish’s minister, Christopher R. Eliot, and the Fields Corner Congregational Church’s minister, the Reverend T.J. Volentine, inspired First Parish members and friends to organize the Fields Corner Industrial School for local children, which evolved into Dorchester House, a multi-service health center.

Today, First Parish is an important resource for Dorchester’s Vietnamese, African-American, Caribbean, Irish, Latino, Haitian, and Cape Verdean residents. The staff collaborates with educators, health-care providers and other local groups to alleviate hunger, violence, racism, and other effects of poverty.

In its nearly four century history, many people have come through First Parish and made an enduring impact on their communities.

First Parish ministers and their periods of tenure: