This book links the molecular evolution of silk proteins to the evolution and behavioral ecology of web-spinning spiders and other arthropods. Craig's book draws together studies from biochemistry through molecular genetics, cellular physiology, ecology, and behavior to present an integrated understanding of an interesting biological system at the molecular and organizational levels. The four chapters on silk form the core of the book. The first outlines the history of silk evolution, and the second explores the genetic code behind the proteins that make up some silks. Next comes an investigation of how the mechanical properties of bulk silk depend on the protein skeleton of the filament. And it is all wrapped up by an explanation of the economics of silk synthesis and its effect on the evolution of the wide range of silk types that some spiders can produce. There is also a chapter on the absence of higher social development in spiders, which, in a twist, is linked to development and related silk-production costs. The brief final chapter summarizes the author's view on the forces that drive silk evolution. Catherine L. Craig is at Harvard University.