The shape of a cell reflects cell-substratum and cell-cell attachment and organization of the cytoskeleton (1–4). Many studies on cell morphology have until recently been purely qualitative for the simple reason that morphological changes resulting from e.g., modulation of cell attachment or perturbation of cytoskeletal components often are so pronounced that quantification may seem unnecessary. However, quantitative determination of cellular morphology greatly expands the possibility of characterizing the role and regulation of macromolecules involved, e.g., in cytoskeletal functions and cellular differentiation.