James H. Sheldon was born on May 15, 1907 in Marietta, Ohio to his father, an attorney, and his mother, a schoolteacher. Due to chronic illness, he was home-schooled for much of his life before receiving a scholarship to attend Marietta College. Graduating in 1927, he went on to earn a Master degree in Political Science from Harvard University in 1928, followed by a stint as an assistant professor at Boston University. There, Sheldon taught international law, constitutional law, and general American government courses until the Great Depression turned his attention to public service.

Working on the administrative staff of the Emergency Relief Administration, he left in 1938 to run for Congress in Massachusetts. Though defeated, he gained respect within the Democratic Party, and returned to the Emergency Relief Administration in 1939 as coordinator of the statistics department. In 1941, Sheldon moved to New York to begin work as Director of the Non-Sectarian Anti-Nazi League, of which he previously served as Administrative Chairman.

The mission of the Anti-Nazi League was to counter Nazi, anti-ethnic propaganda. For example, the organization operated radio programs in both Italian and German to challenge fascist propaganda targeted at the Italian- and German-American communities. Sheldon's experience directing the Anti-Nazi League reinforced his concern for ethnic groups, and he became an authority on political views within American ethnic groups. This led to his involvement with the Nationalities Division of the Democratic National Committee, in which he was active between 1948 and 1968.

Formally established in 1952, the Nationalities Division canvassed ethnic and racial groups of American voters to determine their individual political interests. This information was used to develop campaign strategies for appealing to an increasingly diverse voter population. From its inception, Sheldon served as the Public Relations Director, a role that entailed the drafting of press releases, radio programs, speeches, and other publicized information on behalf of various campaigns. Ultimately, he was responsible for those sections of the Democratic platform which related to ethnic and minority affairs as well as civil rights. As Public Relations Director of the Nationalities Division, Sheldon worked for Adlai Stevenson's 1952 and 1956 presidential campaigns, John F. Kennedy's 1960 presidential campaign, and Robert F. Kennedy's senatorial campaign, among others.

In addition to his position as Public Relations Director of the Nationalities Division, Sheldon was an active journalist who wrote mostly on foreign affairs, serving as a foreign correspondent as well as an officer of the Overseas Press Club of America. Beginning in 1950 and for about twenty years thereafter, he contributed a twice-monthly column on inter-group relations to the American Examiner, a newspaper with an approximate circulation of 200,000 at the time.

Sheldon was also actively involved with the American Association of United Nations, serving two terms as Chairman of its Manhattan Chapter. Other organizations with which Sheldon was affiliated include the United Church of Christ Committee on International Affairs, the Christian Social Action Department of the New York Conference, and the Protestant Council of the City of New York.

Sheldon died in 1975 at the age of 68. His legacy is in his enduring commitment to human rights, both at home and abroad.