Mundella's long-established interest in arbitration resulted in 1872 in his Arbitration (Masters and Workmen) Act (commonly known as Mundella's Act) which made voluntary agreements between managers and workers mutually binding. In the same year he aided the passage of the Coal Mines Regulation Act, paying particular attention to the clauses restricting the working hours of women and children. He continued his campaign for fewer hours for women and children with the introduction of a Nine-Hours Factory Bill in 1872 but it made slow progress and in the summer of 1873, due to opposition from manufacturers, it was withdrawn.