The quotation "all men are created equal" is found in the United States Declaration of Independence and is a phrase that has come to be seen as emblematic of America's founding ideals. The final form of the sentence was stylized by Benjamin Franklin, and penned by Thomas Jefferson during the beginning of the Revolutionary War in 1776. It reads:

"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."

Drawing from Enlightenment philosophy, the phrase reflects the influence of John Locke's second treatise on government, particularly his belief in the inherent equality and individual liberty. Similar ideas can be traced back to earlier works, including medieval and classical sources, which emphasized the dignity and worth of all human beings. Jefferson applied the concept in his original draft of the declaration. The phrase was subsequently quoted and incorporated into the speeches and writings of prominent figures throughout American political and social history. It has been called an "immortal declaration", and "perhaps [the] single phrase" of the American Revolutionary period with the greatest "continuing importance."

The phrase is attested as early as pope Gregory the Great in book XXI of his Moralia in Job (c. 578 – c. 595). and was picked up by Thomas Aquinas, Azo, Hervaeus Natalis, and other medieval thinkers.

Thomas Jefferson, a key figure in drafting the Declaration of Independence, was heavily influenced by French Enlightenment philosophers such as Voltaire, Rousseau and Montesquieu, largely through his friendship with the Marquis de Lafayette. These philosophers, whose writings were often censored, advocated that men were born free and equal. Their ideas profoundly impacted the French Revolution of 1789 and the development of the concept of human rights (droits de l'homme). At the age of 33, Jefferson may also have drawn inspiration from his Italian friend and neighbor Filippo Mazzei, as claimed by John F. Kennedy in A Nation of Immigrants and by Joint Resolution 175 of the 103rd Congress. Additionally, Jefferson might have been influenced by Thomas Paine's Common Sense, which was published in early 1776.

In English history there exist earlier uses of nearly the same phrase. First by the medieval priest John Ball who at the outbreak of the 1381 Peasants Revolt in his famous sermon posited the question "When Adam delved and Eve span, Who was then the gentleman?" and proclaimed "From the beginning all men by nature were created alike". In his 1690 work Second Treatise of Government the philosopher John Locke argues that in the "state of nature" that existed before the formation of governments all men were created equal. Another example is in John Milton's 1649 book called The Tenure of Kings and Magistrates, written after the First English Civil War to defend the actions and rights of the Parliamentary cause, in the wake of the execution of king Charles I. The English poet says: "No man who knows ought, can be so stupid to deny that all men naturally were borne free, being the image and resemblance of God himself ... born to command and not to obey: and that they liv'd so".

In 1776, the Second Continental Congress asked Benjamin Franklin, Thomas Jefferson, John Adams, Robert Livingston, and Roger Sherman to write the Declaration of Independence. This Committee of Five voted to have Thomas Jefferson write the document. After Jefferson finished he gave the document to Franklin to proof. Franklin suggested minor changes, one of which stands out far more than the others: "We hold these truths to be sacred and un-deniable..." became "We hold these truths to be self-evident."

The second paragraph of the United States Declaration of Independence starts: "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the Pursuit of Happiness.-- That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed."