During World War I, Simon was a Red Cross Officer who served in France and was attached to the 304th Sanitary Train of the 79th Division. He formed a branch of the Society a branch of the Society for the Prevention of Cruelty to Children and Animals while living in Sacramento, and in Omaha he took post-graduate courses in philosophy and education at the University of Nebraska. He was president of the Washington, D.C., Board of Education from 1920 to 1923, president of the Central Conference of American Rabbis from 1923 to 1925, a founder of the Synagogue Council of America in 1928, and an organizer of the Washington chapter of the National Conference of Christians and Jews. In 1929, he was appointed a non-Zionist member of the council of the Jewish Agency. In 1912, he and William Rosenau wrote History of Jewish Education.
