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