Upon re-reading, it looks like there is two paths, but both require two steps?
The first part, proposing an amendment:
An amendment may be proposed by a two-thirds vote of both Houses of Congress, OR, if two-thirds of the States request one, by a convention called for that purpose.
Then the second part, ratifying the amendment:
The amendment must then be ratified by three-fourths of the State legislatures, OR three-fourths of conventions called in each State for ratification.