In the 1880s, the Knights of Labor was the largest labor union in the United States, and while they were predominantly Catholic in membership, the Catholic Church wasn't sure Catholics should be Knights. Some priests and bishops were perplexed by the secrecy and perceived radicalism within the union and sought to bar Catholics from joining. Others believed that unions could promote better lives for workers. In 1888 the matter was resolved through the efforts of Knights Leader Terence Powderly and Baltimore Archbishop James Gibbons, when their attempts to gain Vatican permission for Catholics to join the union met with success.