The organ was dedicated in 1973 with 32 ranks and 2 manuals. In 1982, with input from longtime church organist Barbara Dobesh, Holtkamp expanded the organ to 44 ranks and 3 manuals. With 2,326 pipes, it is the largest pipe organ in the state.

The Swell, Great, and Pedal divisions are grouped in the chamber on the south side of the altar, and the Choir division and additional Pedal ranks are in the north chamber. These chambers previously housed the pipes for the church’s original organ, which was built by M.P. Möller in 1928 and reinstalled upon the church’s rebuilding in 1957.

The Holtkamp organ console can roll out to the center of the floor for performances. Its natural keys are made of plumwood, with rosewood for the sharps and flats.

The organ is a testament to First Congregational’s musical legacy. The major gift for the original organ was contributed as a memorial to Maude Boyle Rixon. Its expansion and continued upkeep were made possible by Hubert E. Lillis in memory of his mother, Zoe D. Lillis.