The meetings "At the Frontier of Physics and Biology" are regularly organized workshops in Les Houches, France. They provide an interdisciplinary forum for physicists and biologists working on similar problems, but using perhaps fundamentally different tools and approaches. The first workshop took place in 1991 under the title "Dynamical Phenomena at Interfaces, Surfaces and Membranes". This volume contains the material of the second workshop, which brought together geneticists and developmental biologists with physicists, all studying the development of biological form.