Book: The Economy as an Evolving Complex System II
Edited, with Steven Durlauf and David Lane, Addison-Wesley Series in the Sciences of Complexity, 1997
This is a collection of papers that together comprise the modern approach to complexity in economics. They view the economy as a multiagent system, and focus on the economy-in-process, rather than the economy at equilibrium.
Here is the introduction to the book by Arthur, Durlauf, and Lane. It has much to say about the "Santa Fe approach" to economics.
Read a review by Gerald Silverberg.