A 1953-54 overhaul transformed Valley Forge into an antisubmarine warfare (ASW) support carrier, a function for which her unmodernized flight deck arrangement was still suitable. Redesignated CVS-45, she operated an air group of helicopters and propeller-driven aircraft as the core unit of a task group of destroyers, submarines and other aircraft, whose mission was to aggressively clear the seas of enemy submarines.

Assigned to the Atlantic Fleet, Valley Forge was kept busy developing new ASW techniques and on other functions. She deployed to European waters in 1954. In 1957, she served as test platform for experiments with amphibious "vertical envelopment", using helicopters to land Marines. She was flagship of ASW Task Group Alpha in 1958-59. In early 1960, Valley Forge supported scientific endeavors in Operation "Skyhook", launching three very large balloons in the Caribbean to obtain data on high-altitude cosmic rays. Late that year, following a Mediterranean Sea deployment, she was recovery ship for a "Project Mercury" space capsule. In March 1961, she again began a shipyard conversion, this time to her final role as an amphibious assault ship (LPH).