The Rhode Island Scarlets joined the 1939-40 New England Amateur Hockey League replacing the Rhode Island Marquettes skating against Boston Junior Olympics, Boston Rangers, Springfield Braves and New Haven Brock-Halls. The Scarlets continued to be comprised of the all-stars of the Inter-City Amateur Hockey League. Under manager Jim O'Roarke they finished in a tie for first place and beat the Olympics for the championship in 1939-40. They also participated in the first National AHA championship in the 1939-40 season at the Boston Arena with Boston Junior Olympics (MA), Notre Dame Hockey Club (Waterville, ME), Atlantic City Sea Hawks (NJ), Springfield Braves (MA) and St. Dominques (Lewiston, ME) while losing a thriller in sudden death overtime 5-4 to the champion "97" Club of Boston (MA) in the opening round. In the 1940-41 season they faced off against the Worcester HC (MA), Fitchburg Maroons (MA), Needham Amateurs (MA), Springfield Braves (MA) and the Sacred Heart HC (Concord, NH) and battled the Flying Frenchmen of Woonsocket for the mythical amateur hockey championship of the state losing 4-2 at the Auditorium.
The RI Scarlets played in the Atlantic Amateur Hockey League (AAHL) from 1947 to 1949 (Rhode Island Scarlets 1947-48 and Providence Scarlets 1948-49) guided by coach Ted Dooley. They played against Needham Rockets, Springfield Rifles, New Haven Bears, New York Metropolitans and Boston Junior Olympics. In 1947-48 they won the AAHL championship 3-2 on a late goal by Bob Monahan over the Springfield Rifles. They added the National AHA championship by beating the Grand Rapids Amerks (ND) 3-2 in the opening round and St. Paul 7'Ups of Minnesota 3-1 in the finals at the Sports Arena in Toledo, Ohio on tallies by Alan Porter, Ralph "Swede" Erickson and Jerry Kilmartin. Goalie Al Bentley and Bill Thayer were voted to the all-star team selected by the press. In 1948-49 season, the Scarlets dropped out of the Atlantic loop because Lou Pieri, sponsor of the team, opposed the league rule of permitting players over 21 years old to participate. Pieri wanted an age limit to develop players for professional hockey. Losing star players Billy Thayer and Jerry Kilmartin to the A.H.A team in Sweden also was a factor. They finished the season with 4 and 4 record in 8 games. They also squared off against Trois Riviers Reds of Quebec Canada in a rough battle losing 9-1 in front of 900 spectators at the Auditorium.