The American Gymnosophical Association (AGA) was organized circa 1930 by Herman and Katherine Soshinski. It was one of 3 spin-off groups from the League for Physical Culture that had been organized by Kurt Barthel in 1929. Dr. Maurice Parmelee, Professor of Sociology, City College of New York was its honorary President.
Katherine and Herman Soshinki arrived in the US in 1923 from Germany as librarians of the New York Public Library. They had become familiar with nudist practice in Germany from 1918–23. Once in the US they continued their subscription to the German newspapers where they saw the advertisements by Kurt Barthel soliciting German residents to assist in the formation of nudist groups. They joined the group, the League of Physical Culture spending time with others at leased farms in Westchester County in summers and gymnasiums and pools in New York in the winter before organizing the American Gymnosophical Association. Due to the anti-nudity laws in New York they searched for a location which led them to Rock Lodge. Membership soon grew to over 300 and national nudist conventions were held at Rock Lodge Club in 1936, 1938, and 1941.
Rock Lodge Club compared most favorably with the other camps, not only in the scenic beauties, conveniences, and housing facilities, but with the personnel of the membership body at large, as well as the directors in particular. The group had an office in Manhattan and by 1933 had leased an 11-acre (45,000 m2) camp in the foothills of the Catskills and accepted another farm of 60 acres (240,000 m2) nearer the city. Miss Ruth Winkler was the secretary of the Association.
Like other groups interested in nudism, the American Gymnosophical Associates, maintained a well-equipped gymnasium in New York City during the winter months, where calisthenics and other exercises were indulged in under expert guidance.
A 1932 painting by artist Richard Ederheimer (1878–1959) indicating nudist activities at Rock Lodge Club is in the collection of the New Jersey Historical Society.
In 1936 looking to expand its operation in the winter months the AGA advertised for a secretary for its new camp Mossy Oaks located in Lake Thonotossa, Tampa, Florida which was, at that time, Tampa's only nudist colony. By 1939 both locations had been approved for National American Sunbathing Association charter, Oakland, NJ. The AGA had to discontinue renting country places in Florida in 1943 because of financial difficulties due to World War II.