From DNA to Diversity Molecular Genetics and the Evolution of Animal Design. Sean B. Carroll, Jennifer K. Grenier, and Scott D. Weatherbee. Blackwell Science, Malden, MA, 2001. 230 pp. Paper, $44.95, £33.95. ISBN 0-632-04511-6. Genomic Regulatory Systems Development and Evolution. Eric H. Davidson. Academic Press, San Diego, 2001. 273 pp. $49.95. ISBN 0-12-205351-6. The evolution of developmental gene networks is the focus of both of these books. Carroll et al . provide an easy-access introduction to the topic that relies on lessons drawn from a handful of model organisms. Davidson stresses general principles in his less accessible but deeper account, which is aimed at his colleagues in the "evo-devo" field.