Praeger graduated from Rensselaer Polytechnic Institute in 1915. He served in the U.S. Navy during World War I, after which he spent time at the architectural office of Bertram Goodhue and the New York City engineering firm Madigan-Hyland.
In 1934, as chief engineer for the City of New York Department of Parks & Recreation, Praeger surveyed all New York City parks.