Tresca joined the revolutionary syndicalist Industrial Workers of the World (IWW) in 1912, when he was invited by the union to Lawrence, Massachusetts to help mobilize the Italian workers during a campaign to free strike leaders Joseph Ettor and Arturo Giovannitti, jailed on false murder charges. After the victorious strike in Lawrence, Tresca was active in several strikes across the United States; the Little Falls, New York textile workers' strike (1912), the New York City hotel workers' strike (1913), the Paterson silk strike (1913), and the Mesabi Range, Minnesota, miners' strike (1916). He was arrested several times and jailed for nine months awaiting trial for murder in conjunction with the Minnesota action, ultimately being released without going to trial.