Mary Dierickx, Principal of Mary B Dierickx since its founding in 1977, is a graduate of the Columbia University School of Architecture's Historic Preservation program and has been active in the preservation field for more than 25 years. She has written several articles and monographs on preservation topics in such publications as the Association for Preservation Technology Bulletin and the Municipal Engineers Journaland is the author of the NYCDGS/Cooper Union publication The Architecture of Literacy: Carnegie Libraries of New York City. Her firm has participated in such award-winning projects as: the Whitby Castle Restoration in Rye, NY (Rye Landmarks Advisory Committee), the Gardiner Tyler House addition, Staten Island, NY (Victorian Society, NYC Chapter) The Center Restoration in NYC (Victorian Society, NYC Chapter; Landmarks Preservation Commission, Landmarks Conservancy), Surrogates Court/Hall of Records, a publication and exhibition (Metropolitan Chapter of the Victorian Society and NYC Department of General Services Professional Service Award), and DGS Inventory of Landmark Building Plans and Drawings, a publication (NYC Department of General Services Professional Service Award).

Mary Dierickx has given lectures on preservation for the National Trust for Historic Preservation, the Association for Preservation Technology, the New-York Historical Society, the Cooper Hewitt National Design Museum, the American Library Association, the Historic Districts Council, the NYC Landmarks Preservation Commission, and the Department of General Services. Topics include the Carnegie libraries, the preservation of wooden structures, historic sheet metal ceilings and roofing, the preservation profession, international preservation, historic towns, the historic structure report, and New York City history.

Mary Dierickx currently serves as chairman of the board of trustees of the James Marston Fitch Charitable Foundation, president of the Fine Arts Federation of New York, a civic group founded in 1895, and as a member of the preservation committee of the Municipal Art Society in NYC. She is a member of the United States Committee of the International Council on Monuments and Sites (US/ICOMOS) Scientific Committees on Wood and Historic Towns. She is a former board member and treasurer of US/ICOMOS and has served on the boards of the New York Chapter of the Association for Preservation Technology, the New York Chapter of the Society of Architectural Historians as secretary, the New York Chapter of the Victorian Society as chair of the Preservation Committee, the Metropolitan Historic Structures Association as chair of the Preservation Committee, and Preservation Alumni of Columbia University, where she was president.