three-quarters of the states agreeing adapt as our country grew Bill of Rights Institute three-quarters of the states agreeing 2/3 of both Houses of Congress is required 2/3 of both Houses of Congress is required add numerous amendments to make up for their failures U.S. constitution has been amended just 17 times billofrightsinstitute.org three-quarters of the states agreeing 2/3 of both Houses of Congress is required 2/3 of both Houses of Congress is required U.S. constitution has been amended just 17 times