William Street School, also known as Horace Mann School, is a historic school building located at Huntington, Huntington County, Indiana. The original section was built in 1895, and is a 2+1⁄2-story, rectangular plan brick building with Romanesque Revival and Queen Anne style design elements. It sits on a raised basement, has a rounded corner and projecting gable, bell tower, and has a multi-gabled slate roof. A two-story, Neoclassical style addition was built in 1926. It was listed on the National Register of Historic Places in 1986. It is located in the Drover Town Historic District.