In 1932 she was appointed as General Secretary to the NCL, and moved to New York, where she lived for five years; working closely with social workers and recruiting staff for relief and welfare agencies created under the New Deal.

[9] In July 1937, at age 55, Mason moved to Atlanta and started working at the Textile Workers Organizing Committee offices and became the CIO's "roving ambassador" for the next 16 years.

[10] For Mason, the CIO was "a training ground for citizenship" for Southern workers, a vehicle "to bring democracy to the South" and the means to alleviate the economic and racial injustices experienced by minorities and the poor.

She cornered hostile sheriffs, judges, newspaper editors, politicians and ministers, explaining workers' rights to organize and bargain under the new federal statutes and promoting an understanding of the need for unions.

Her social status as a Southern lady and the daughter of an old, respected Virginia family often gained her access to political and community leaders when others were denied.

- Myles Horton[7]Miss Lucy's success also rested on her blunt speech, her calm yet steely demeanor and her ability to bring civil liberties violations to the attention of federal officials, including President Franklin D. Roosevelt.

For example, Mason convinced Roosevelt to send a special federal investigator to Memphis in 1940 in the wake of physical attacks on the United Rubber Workers' organizers who were trying to create an interracial union.

Mason was dedicated to ending white supremacy in the South, where she was a founding member of the Southern Conference for Human Welfare and she was a frequent speaker at interracial gatherings.

[4] In 1952, Lucy Randolph Mason's autobiography was published called To Win These Rights, which contained an introduction written by her close friend, Eleanor Roosevelt.