Bryn Athyn is a home rule municipality in Montgomery County, Pennsylvania. It was formerly a borough, and its official name remains "Borough of Bryn Athyn". The population was 1,375 at the 2010 census. It was formed for religious reasons from Moreland Township on February 8, 1916. Bryn Athyn is surrounded by Lower Moreland Township.

Montgomery County, colloquially referred to as Montco, is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population of the county was 856,553, making it the third-most populous county in Pennsylvania after Philadelphia and Allegheny counties. The county is part of the Southeast Pennsylvania region of the state.