Translational control of mRNAs regulates the spatiotemporal production of the proteins they encode. Further refinement of mRNA and protein distribution patterns is brought about by regulation of transcript stability. Genetic and molecular analyses in Drosophila can provide unparalleled insight into the developmental functions of the modulation of mRNA translation and stability. These mechanisms play a key rob in regulating the production of cell fate determinants, cell cycle regulators and molecular chaperones. (C) 1997 Academic Press Ltd.