The ship then conducted training exercises out of Little Creek before entering the Norfolk Navy Yard for conversion to an LST flotilla flagship, involving the installation of much new communications equipment.

She continued participating in exercises and assault landings in the Caribbean and returned to Norfolk, Virginia, on 14 May 1957 to resume local operations and LST training.

During her subsequent Mediterranean tour of duty, she took part in North Atlantic Treaty Organization (NATO) landing exercises at Saros Gulf, Turkey, and visited ports in Turkey, mainland Greece, mainland Italy, Crete, and Sicily before returning to the United States on 12 February 1958 and resuming local operations out of Little Creek.

On 16 June 1959 Terrebonne Parish commenced an "inland seas" cruise, transiting the St. Lawrence Seaway and calling at Iroquois, Cape Vincent, and Port Weller, Ontario, Canada; Ashtabula, Ohio; Kenosha, Wisconsin; Chicago, Illinois; Milwaukee, Wisconsin; Cleveland, Ohio; Erie, Pennsylvania; Port Colburne, Ontario; and Rochester, New York, before returning to her home base at Little Creek on 6 August.

During these emergency preparations, Terrebonne Parish operated with the Atlantic Fleet Amphibious Force through December 1962, when the Cuban Missile Crisis finally subsided.

Terrebonne Parish remained in the Mediterranean until February 1964 before returning to the United States for amphibious exercises in the spring of 1964 at Onslow Beach, North Carolina, and off Cape Pendleton, Virginia.

After refresher training, Terrebonne Parish got underway for the Caribbean on 3 March 1966 to begin a four-month deployment to participate in exercises and operations involving beachings and landings.

During this Caribbean tour, a locking device was developed for the sand flaps on the ship's bow doors to keep them secure while underway, and it was installed on Terrebonne Parish in January 1966 at San Juan, Puerto Rico.

While she was at Taormina, Sicily, in late July 1967, volunteers from her ship's company and embarked Marines went ashore to battle a raging brush fire threatening the town of Giardini.

In September 1970, Terrebonne Parish steamed in company with the flagship of Commander, Amphibious Forces, Atlantic – amphibious force command ship USS Pocono (AGC-16) – and USS Spiegel Grove – to Halifax, Nova Scotia, Canada, and encountered a confluence of two storms in which she took "green water" on occasion, 25 feet (7.6 meters) over her bows, heavily damaging many weather deck fixtures and equipment.

In 1971, still homeported at Little Creek, Virginia and operating under command of Amphibious Forces, Atlantic, Terrebonne Parish deployed to the Caribbean for exercises and training activities.