This article was originally written for the online discussion series “Athenian Law in its Democratic Context,” organized by Adriaan Lanni and sponsored by Harvard University’s Center for Hellenic Studies. Its purpose is to introduce, very briefly, the institutions of the Athenian democracy during the late 5th century BCE through the end of the radical democracy in the late 4th century. This is a companion-piece to “The Development of Athenian Democracy,” also written for the CHS’s discussion series.