He also organized many choral societies in both New York City and in Washington, D.C. The New York Syncopated Orchestra, which he founded, toured the United States in 1918 and went to England in 1919 for a command performance for King George V. Known also as the Southern Syncopated Orchestra, it sought to bring jazz and ragtime to other countries, and toured in England and Europe. Among his company were assistant director Will Tyers, jazz clarinetist Sidney Bechet, and Cook's wife, Abbie Mitchell. Cook also mentored younger musicians, such as Eubie Blake and Duke Ellington, who became renowned in successful careers of their own.