Gardiner Hallock joined the Thomas Jefferson Foundation in 2011. Since February 2024, he has served as the Interim President of the Thomas Jefferson Foundation. Before being appointed Interim President, Gardiner helped to preserve the Foundation's historic architecture and landscapes as a member, and then Director, of the Restoration Department. Later he became the Director of the Restoration, Curatorial, and Facilities Departments. More recently he was Vice-President of Architecture, Lands, and Facilities.  

A native of Albemarle County, Virginia, Gardiner served as the Restoration Manager at George Washington’s Mount Vernon after receiving his Master of Science in Historic Preservation from the University of Vermont in 2000. Later he was Director of Architectural Research during the restoration of James Madison’s Montpelier. Between Mount Vernon and Montpelier, Gardiner co-founded a historic preservation consulting firm specializing in preservation planning and historic rehabilitation tax credits. 

Gardiner lives in Keswick, Virginia, with his wife, Jennifer Hallock, and their two sons, Henry and Holland.