The Solonian Constitution was the earliest Athenian constitution, created by Solon in the early 6th century BC.

Solon wanted to revise or abolish the older laws of Draco, which had not solved any of the problems in Athens despite inflicting harsh penalties for almost every crime. Under Solon's reforms, all debts were abolished and all debt-slaves were freed. The status of the hectemoroi (the "one-sixth workers"), who farmed in an early form of serfdom, was also abolished. These reforms were known as the Seisachtheia, the "shaking off of burdens."

Solon's constitution reduced the power of the old aristocracy by making wealth rather than birth a criterion for holding political positions. Citizens were also divided based on their land production: pentecosiomedimi (over 500 bushels of produce), hippeis (300-500 bushels), zeugitae (200-300 bushels), and thetes (below 200 bushels, as well as citizens with no wealth tied to the land). Each division had different rights; for example, the pentecosiomedimi could be archons, while thetes could only attend the Athenian assembly (the Heliaia).

The Heliaia was given the right to hear appeals, and Solon also created the Boule as a higher assembly. Both of these were meant to decrease the power of the Areopagus, the aristocratic council.

The only parts of Draco's code that Solon kept were the laws regarding homicide. The constitution was written as poetry, and as soon as it was introduced, Solon went into self-imposed exile for 10 years so he would not be tempted to take power as a tyrant.