Spectrin, together with actin and a number of other accessory proteins, forms a submembrane cytoskeletal network in the human erythrocyte ghost. Through an elegant combination of structural, biochemical, and genetic studies, spectrin was shown to be an important determinant of erythrocyte shape and membrane stability. Genetic studies of a novel nonerythroid spectrin (beta H) in Drosophila and Caenorhabditis elegans now reveal that spectrin can influence the shape and stability of whole organisms. Nonerythroid spectrins are proposed to have roles in cell adhesion, establishment of cell polarity, and attachment of other cytoskeletal structures to the plasma membrane. The phenotypes of the beta H spectrin mutations provide an exciting biological context in which to evaluate these roles and perhaps to uncover new ones.