The Constitution contains within itself the process of changing it. The amendment process is described in Article 5. Amendments can be proposed in Congress when 2/3rd of both Houses agree. The states can play a role in proposing changes to the Constitution as well: 2/3rds of the state legislatures must call Conventions to propose amendments. Whether amendments are first proposed by the states or Congress, 3/4ths of the states must ratify (or approve) them before they become a part of the Constitution-the supreme law of the land. The Constitution, with its 27 amendments, has been amended only 17 times since the first 10-which make up the Bill of Rights-were ratified in 1791