ABSTRACT It is convenient to distinguish between three related problems in development: cell differentiation; pattern formation, which is about spatial organization; and morphogenesis in the strict sense, which is about change in form, particularly of cell sheets, but includes cell migration (Wolpert, 1981; Wolpert & Stein, 1984). All these need to be linked to gene action. If one looks forward over the next five to ten years then the future of craniofacial biology lies in molecular cell biology. This is not to say that all the problems at the tissue level have been solved, quite the contrary, but rather that the emphasis must now be at the cell and molecular level.