The Thirteenth Amendment may refer to the:

• Thirteenth Amendment to the United States Constitution, which abolished slavery and involuntary servitude, except as punishment for a crime
• Thirteenth Amendment of the Constitution of India, established the Indian state of Nagaland
• Thirteenth Amendment of the Constitution of Ireland, which specified that the prohibition on abortion would not limit freedom of travel
• Thirteenth Amendment to the Constitution of Pakistan, which stripped the president of many of his reserve powers
• Thirteenth Amendment of the Constitution of South Africa, which re-enacted provisions of the Twelfth Amendment
• Thirteenth Amendment to the Constitution of Sri Lanka, which created Provincial Councils in Sri Lanka