In this lecture, Professor Kagan describes the mechanics of the Delian League and its transformation into the Athenian empire. This transformation caused Athens to rival Sparta as an equal in power and prestige. He also argues that this process took place rather smoothly due to the good relations between Sparta and Athens. Professor Kagan argues that Cimon the Athenian generally played an important part in this development. Finally, Professor Kagan begins to describe the workings of Athenian democracy by comparing it with modern American democracy.