The Ethan Allen class of fleet ballistic missile submarine was an evolutionary development from the George Washington class. Together with the George Washington, the Lafayette, the James Madison, and the Benjamin Franklin classes, they comprised the "41 for Freedom."
Rather than being designed as Skipjack-class attack submarines with a missile compartment added, the Ethan Allens were designed from scratch as fleet ballistic missile submarines carrying the Polaris A2 missile. In the early and mid-1970s, they were further upgraded to Polaris A3s