The molecular cascades that control craniofacial development have until recently been little understood. The paucity of data that exists has in part been due to the complexity of the head, which is a unique, and possibly one of the most intricate regions of the body. However, the generation of mouse mutants, the identification of gene mutations that cause human craniofacial syndromes, together with classical embryological approaches in other species has now given significant insight into how the head develops. These studies have emphasized how unique the head actually is with each individual part governed by a distinct set of signalling interactions, again demonstrating the complexity of this region of the body.

1 Introduction.- 2 Neural and Head Development Are Intimately Linked.- 2.1 Exencephaly.- 2.2 Holoprosencephaly.- 3 Fate and Roles of the Neural Crest, Mesoderm, and Epithelium.- 3.1 Neural Crest.- 3.2 Mesoderm.- 3.3 Epithelium.- 4 Neural Crest Development.- 4.1 Generation.- 4.2 Segregation ofHindbrain Neural Crest.- 4.3 Migration.- 4.4 Proliferation and Survival.- 5 Growth and Patterning of the Face and Branchial Arches.- 5.1 Patterning of the Face and Branchial Arches.- 5.2 Growth Factor Regulation of Outgrowth of the Facial Primordia.- 5.3 Fusion of the Facial Primordia.- 6 Skeletal Development.- 6.1 Induction of Skeletal Structures.- 6.2 Skeletal Growth and Differentiation.- 7 Muscle Development.- 7.1 Origins and Migration.- 7.2 Muscle Differentiation.- 8 Human Craniofacial Syndromes.- 8.1 Riegers Syndrome.- 8.2 Treacher-Collins Syndrome.- 8.3 DiGeorge Syndrome.- Summary.- References.