Article V establishes two methods for ratifying constitutional amendments, with Congress deciding which one to use: state legislatures can vote to ratify, or states can call special conventions where elected delegates vote. Three-fourths of states (38 out of 50) must approve for an amendment to take effect.
Congress has overwhelmingly preferred the legislature method—26 of the 27 ratified amendments went through state legislatures. The sole exception was the Twenty-first Amendment repealing Prohibition in 1933, which Congress sent to state conventions to bypass temperance-supporting legislators and reflect popular will on a moral question.
The Framers included both options to give flexibility in the amendment process. Legislatures offer a faster, more streamlined path since they already exist and meet regularly. Conventions require states to organize special elections for delegates and set up new procedures, but they can better capture public sentiment on specific issues. Neither method has ever been used to call a constitutional convention under Article V's other proposal mechanism.