Petrillo, James Caesar (pētrĭlˈō, pĭ–) [key], 1892–1984, American labor leader, president of the American Federation of Musicians (1940–58), b. Chicago. In 1915 he became president of the American Musicians' Union. However, three years later he joined the American Federation of Musicians (AFM) and in 1922 was elected the local's president. He built his local into a highly disciplined organization and became a force in municipal politics. As national president of the American Federation of Musicians, he called several strikes against radio, television, and recording companies in order to strengthen the AFM and to combat the increased use of technological devices that lessened employment for musicians. Petrillo continued to serve (until 1963) as president of the Chicago branch of the AFM after his resignation as national president.