Waldron joined the Workers Party in 1926. In 1929, Waldron fled to the Soviet Union to avoid criminal charges for his political activities under the California Criminal Syndicalism Act. Waldron returned to the United States in 1935 and assumed the pseudonym Eugene Dennis. Dennis became General Secretary of the party after the expulsion of Earl Browder and was a staunch supporter of the Moscow line. On July 20, 1948, Dennis and eleven other party leaders, including Party Chairman William Z. Foster were arrested and charged under the Alien Registration Act. Foster was not prosecuted due to ill health. As Dennis and his co-accused had never openly called for the violent overthrow of the United States government, the prosecution depended on passages from the works of Karl Marx and Vladimir Lenin that advocated revolutionary violence and on the testimony of former members of the party who claimed Dennis and others had privately advocated the use of violence. After a nine-month-long trial and the imprisonment of the defense lawyers for contempt of court, Dennis and his co-defendants were found guilty and sentenced to five years imprisonment. They appealed to the Supreme Court of the United States, which ruled 6–2 against the defendants on June 4, 1951 in Dennis v. United States,. The Court later scaled back its Dennis opinion in Yates v. United States and rendered the broad conspiracy provisions of the Smith Act unenforceable. Eugene Dennis was imprisoned in the years 1951-1955, according to the verdict in his case. Dennis remained General Secretary until 1959, when he succeeded Foster as party chairman and held that position until his death in 1961.
The elections and the outlook for national unity., New York, Workers Library Publishers, 1944.
America at the crossroads: postwar problems and communist policy., New York, New century publishers, 1945.
Marxism-Leninism vs. revisionism., New York, New Century publishers, 1946.
The people against the trusts; build a democratic front to defeat reaction now and win a people’s victory in 1948., New York, New Century Publishers, 1946.
What America faces: the new war danger and the struggle for peace, democracy and economic security., New York, New century publishers, 1946.
Let the people know the truth about the Communists which the un-American committee tried to suppress., New York, New century publishers, 1947.
New York : National Office, Communist Party, 1948.
Ideas they cannot jail., New York, International Publishers, 1950.
Letters from prison. Selected by Peggy Dennis., New York, International Publishers, 1956.
The Communists take a new look., New York, New Century, 1956.
