Courtney Langdon was born at Rome, Italy, where his father, William Chauncy Langdon, was founder and first rector of the American Episcopal Church. His mother was Hannah Agnes Courtney of Virginia. Returning to America in 1862, his father became a member of the joint committee of the American Episcopal Church on Italian Catholic reform, and was sent as a representative to Italy in 1867, residing at Florence from that date until 1873. In 1873 his father founded and was the first pastor of Emmanuel Church, Geneva, Switzerland. The father became rector of Christ Church, Cambridge, Massachussets, in 1876.