  We present a formal treatment of the Crowd-Anticrowd theory of Minority Games
played by a population of competing agents. This theory is built around a
description of the crowding which arises within the game's strategy space.
Earlier works have shown that this theory provides a simple, yet quantitatively
accurate explanation of the time-averaged behavior of these multi-agent games.
We also discuss the extent to which the Crowd-Anticrowd approach provides a
useful tool for analyzing a wider class of Complex Systems.
