The Moffatt-Ladd House, also known as the William Whipple House, is a historic house museum and National Historic Landmark at 154 Market Street in Portsmouth, New Hampshire, United States. The 1763 Georgian house was the home of William Whipple (1730-85), a signer of the Declaration of Independence and Revolutionary War general. The house is now owned by the National Society of Colonial Dames in New Hampshire, and is open to the public.