The interactions of both normal and transformed cells with their environment is mediated to a large extent by the cell surface. Succinylated concanavalin A (succinyl-Con A) is a nontoxic and nonagglutinating derivative of the jack-bean lectin concanavalin A. Succinyl-Con A, presumably through an interaction with the cell surface, reversibly inhibits the growth of normal cells and restores a normal growth phenotype to transformed cells. Whereas at high cell densities migration was inhibited, it turned out that at low cell densities where cells are not in contact with each other, cell movement was not affected by succinyl-Con A. Together with some additional observations, this suggests that this lectin derivative increases cell-to-cell adhesion in culture and thereby may influence cell migration. An increase in cell-to-cell adhesion by this lectin derivative may not be brought about simply by physically linking cells together. It occurs after a lag time, possibly by inducing surface changes. The relationship between cell adhesion in culture, cell movement, and cell growth is discussed.