Article 5, Section 1

Short Version -- This is a summary of the important issues covered in this section of the U.S. Constitution. 

• Amendments may be proposed by a two-thirds vote of both houses of Congress.
• Two-thirds of the state legislatures may ask Congress to call a convention for the purpose of proposing amendments to the Constitution.
• Amendments must be approved by three-fourths of the state legislatures or by conventions in three-fourths of the states.

Long Version -- This is the text of the Actual U.S. Constitution.

The Congress, whenever two thirds of both houses shall deem it necessary, shall propose amendments to this Constitution, or, on the application of the legislatures of two thirds of the several states, shall call a convention for proposing amendments, which, in either case, shall be valid to all intents and purposes, as part of this Constitution, when ratified by the legislatures of three fourths of the several states, or by conventions in three fourths thereof, as the one or the other mode of ratification may be proposed by the Congress; provided that no amendment which may be made prior to the year one thousand eight hundred and eight shall in any manner affect the first and fourth clauses in the ninth section of the first article; and that no state, without its consent, shall be deprived of its equal suffrage in the Senate.