In Scranton in 1876, Powderly joined the local branch of the Knights of Labor. He quickly moved up in the union. By 1879, he became the leader (his title was "Grand Master Workman"). While he was the leader, the Knights of Labor had the most members and most influence it ever had. After 1886, the Knights declined. In a struggle for power, Powderly was removed. His rival John William Hayes became the leader. Having lost his position, Powderly studied to become a lawyer. In 1894 he was admitted to the Bar (became a lawyer) in Pennsylvania. For this he was thrown out of the Knights of Labor.