Leonard Porter Ayres (1879 – 1946) was an American educator, born at Niantic, Conn. He received his college and graduate training at Boston, Harvard, and Columbia universities. He began teaching in 1902 as one of the first to carry American ideas and methods to Puerto Rico. There he was appointed superintendent of schools in the districts of Caguas and San Juan, and later general superintendent of all the public schools on the island. Having returned to live in the United States, he was made head of the division of statistics in the Playground Association of America. Beginning in 1908, he was prominently identified with the work of the Russell Sage Foundation, especially as chairman of the committee in charge of the Backward Children Investigation. In 1908-09 he lectured on education at New York University. Very many of his articles in educational journals have been reprinted, among them, The Effect of Promotion Rate on School Efficiency (1913). His writings on educational subjects , besides reports and contributions to periodicals, are: Ayres apparently tallied a count of the US Army battle deaths for World War I. He served as a Major during the war or shortly thereafter. Ayres was recalled to active duty in 1940 with the rank of Brigadier General. He retired in 1942 and was awarded the Distinguished Service Medal.