The service will take place at 5 p.m. at Christ & Holy Trinity, 75 Church Lane. A free-will offering will suppport a summer mission trip by the host church's youth group, Holy Trinity said in a news release.
A reception with refreshments will follow the service.
The program is part of the host church's Music & Arts Series, and choral selections will range from English composers of the early 17th century to American composers of the 21st century.
The music directors of both churches -- Robert Kwan from the Southport church and Michael Burnett from the host church -- will direct the choirs and accompany them on Christ & Holy Trinity's 1933 Möller organ.
For more information, visit www.chtwestport.org/concerts or call 203-227-0827.