Dr. Bell became a member of the Canadian Historical Association circa 1937. This organization was established in 1922 to promote historical research and scholarship. Dr. Bell became a life member of the Association in 1949.
He was also a very involved member of the Nova Scotia Historical Society, founded in 1878. His membership with this Society dates to 1933. He contributed his first paper to the Society in 1947. In it he recounted garrison life of a Hessian soldier in Halifax during the American Revolution. 
In 1948, Dr. Bell was elected to the Executive of the Society, serving as Vice-President 1948-1949. That same year he presented a paper to the Society that was based on an unpublished manuscript left by his great-uncle, John A. Bell. It documented life in Halifax circa 1828 giving many personal reminiscences. This article was published in Collections of the Nova Scotia Historical Society in 1949. 
Winthrop Bell was elected President of the Nova Scotia Historical Society in 1951. His responsibilities included organizing the speakers and a number of other administrative tasks. One of the chief aims of his tenure in the role was to establish a Genealogical Committee. He worked closely with Mr. C. St. C. Stayner of Halifax to establish by-laws for this committee and to determine membership issues. Dr. Bell's rationale in developing the committee was stated as follows:
"One very practical consideration bearing on the question, here, is that, at present, the Nova Scotia Archives staff is plagued, and altogether too much of its time is taken up by genealogical enquiries. ... Were there a genealogical organisation here, however, the Archives could quite courteously refer enquirers to that organisation, which could reasonably make a charge for its services... The Archives could well afford to place space at the disposal of a genealogical organisation, for that reason." 
His work was initially successful. However, the organisation originally envisioned by Dr. Bell waned and was only re-established thirty years later with the creation of the Genealogical Association of Nova Scotia (GANS) in 1982.
Due to ill health Dr. Bell stepped down from his role as President of the Nova Scotia Historical Society in 1953. However, he was subsequently asked to present details of his research into the lives of two of his ancestors, the Hon. Hugh Bell and Brigadier-General Jedidiah Preble. 
The last article that Dr. Bell prepared for the Society was about a group of settlers from the Azores Islands of Portugal that settled in Nova Scotia in 1750. Dr. Bell's scholarship and service were recognized that same year when he was made a life member of the Society. 
For his work on the "Foreign Protestants" Dr. Bell was awarded a Certificate of Merit by the American Association for State and Local History in 1961 and was lauded by the Canadian History Association in 1963.
 Bell, Winthrop P. "A Hessian conscript's account of life in garrison at Halifax at the time of the American Revolution." Collections of the Nova Scotia Historical Society. (27) 1947: 125-146.
 Bell, Winthrop P. "A Halifax Boyhood of One Hundred and Twenty Years Ago." Collections of the Nova Scotia Historical Society. (28) 1949: 106-132. [Read before the Nova Scotia Historical Society - March 5, 1948]
 Mount Allison University Archives, Winthrop Pickard Bell fonds, Letter from Winthrop Bell to Prof. J.B. Brebner, April 19, 1952, 6501/13/1 - File No. 3 - Item no. 2.
 Bell, Winthrop. Brigadier-General Jedidiah Preble (1707-1784) and his participation in Nova Scotia history. Halifax: Halcraft Printing Ltd., 1954.
 Bell, Winthrop. "The Settlers from the Azores, 1750." Collections of the Nova Scotia Historical Society. (31) 1957: 19-37).