[5] He was arrested in January 1904[6] for conducting a radical study circle for young workers,[7] although according to his children his offense was merely recommending Tolstoy to someone at the library.

[8] He spent eight months in jail,[9] during which he met older, more radical socialists belonging to the General Jewish Labour Bund, and was converted to their cause.

In 1907, Vladeck was named as a Bund delegate to the 5th Congress of the Russian Social Democratic Labour Party in London, representing the Vitebsk district under the psuedonym "Broches.

In 1908 he left Europe for North America, landing at Ellis Island on Thanksgiving Day, soon after which he began to immerse himself in the study of American history and culture.

[13] During this time, Vladeck's idealistic perception of America would be tempered by encounters with Jim Crow racism in the South and violent strikebreaking in Philadelphia.

[14] He became a naturalized citizen in 1915 and made his first run for public office the same year,[11] campaigning unsuccessfully for Judge of the Philadelphia Orphans' Court on the Socialist ticket.

[11] During that year's elections, he became an important ally of Meyer London, a fellow Jewish emigrant from the Russian Empire, and aided him in his re-election campaign.

When the Russian Revolution broke out a few months later, he celebrated the downfall of the Tsardom with the rest of the Forward staff, but decided that America had become his home and chose not to return.

[14] Campaigning in both Yiddish and English, Vladeck drew heavy crowds and would ultimately win the election against Democratic-Republican fusion candidate Harry Heyman by a margin of 779 votes out of 4,825 cast.

[17] The Socialists elected seven alderman to the 70-member board, and as a result most of their measures aimed at government reform, municipal ownership, and workers' rights were defeated by the Tammany majority.

[10] He finally lost re-election in 1921 after the Socialist Party splintered,[10] his district was gerrymandered, and the Republicans and Democrats fielded another fusion candidate.

He also convinced the Forward Association to sponsor WEVD, a radio station set up by the Socialist Party in memoriam of its recently-deceased leader Eugene V.

[14] Despite his earlier patronage of Vladeck, Forward editor Abraham Cahan came to harbor a deep resentment towards his subordinate for reasons that were not entirely clear.

[10] When Cahan began to lobby for a Jewish state, Vladeck rebuked him as follows: Zionists and Communists have one thing in common—both are extremist fanatics to the point of madness.

[18] Vladeck returned to the electoral arena in 1930, one year into the Great Depression, with a run for Congress in New York’s 8th district, covering the southern half of Brooklyn.

He lost to incumbent Democrat Patrick J. Carley but polled an impressive 17 percent of the vote, giving hope to some in the party that an electoral comeback was on the horizon.

[11] When Adolf Hitler came to power in Germany in 1933, Vladeck saw him as a threat both to Jews and labor, and resolved to use his standing to organize American resistance to the Nazi regime.

"[25] Vladeck and the JLC returned to the AFL's 1934 convention and convinced the federation to establish the Chest for Liberation of Workers in Europe,[11] which set aside $250,000 for assisting the labor movement in fascist countries.

In 1924 he (along with the rest of the party) endorsed Progressive Senator Robert M. La Follette’s presidential candidacy,[10] and a decade later he was one of the most vocal “eastern” supporters of Socialist-Progressive fusion in Wisconsin.

Founded in 1936 with the purpose of securing president Franklin D. Roosevelt's re-election, the American Labor Party brought together New York's Socialist and garment trades leaders in a bid to attract pro-New Deal, anti-Tammany votes.

[11][14] The party supported Fiorello La Guardia's bid for re-election in 1937 and became part of judge Samuel Seabury's Citizens Non-Partisan Committee, an anti-Tammany electoral coalition that included Republicans, American Laborites, City Fusionists, and Socialists.

[39] Vladeck, Morris, and La Guardia would form a sort of "troika" that had breakfast together every morning before Council sessions to plan the legislative work of the day.

[11] Vladeck held the office of majority leader for the next eight months, during which he developed a reputation as a calm but firm parliamentarian, only occasionally rising to challenge the bigotry of his fellow politicians.

Among the speakers at the service were Governor Herbert Lehman, Mayor Fiorello La Guardia, Senator Robert F. Wagner and Socialist leader Norman Thomas.