Charleston sailed from Norfolk, Virginia on 24 February 1937 to join Squadron 40T, in which she visited Dubrovnik, Yugoslavia, Trieste, Naples, Italy, and Algiers before returning to the Charleston Navy Yard for updating on 24 April.
From 21 April-3 October 1938, and from 4 January 1939 - 27 June 1940, she returned to the Caribbean to conduct off-shore patrols and good will visits, and on the second trip she served as flagship.