Irwin Thornton Catharine (October 22, 1883 – March 3, 1944) was the chief architect of Philadelphia public schools from 1920 until his retirement in 1937. Buildings built during Catharine's tenure ranged from Gothic Revival, as in the case of Simon Gratz High School, to Streamline Moderne, as in his last project, Joseph H. Brown Elementary School. He died in Philadelphia in 1944.
Catharine succeeded Henry deCoursey Richards as the main school designer in Philadelphia. From 1918 to 1937, his work added 104 new buildings (replacing 37 existing ones), added wings to 26 other schools, and otherwise improved at least 50 other schools.[1]: 13
A number of his works are listed on the U.S. National Register of Historic Places.[2]