The organization of the principal cytoskeletal components (actin, tubulin and 10 nm filament protein) have been compared by immunofluorescence microscopy in two populations of chick heart fibroblasts, previously shown to be adapted respectively for rapid, directed migration or adhesion and growth. We find that neither microtubule nor 10 nm filament distributions after significantly during the conversion from the migratory to the stationary state but in contrast there are significant differences in the organization of actin. The stationary cells possess more numerous and thicker stress fibre bundles. The variety of patients observed in the migratory cells are documented and the possible roles of the different components of the cytoskeleton in cell locomotion are discussed.