The C1H3 monoclonal antibody recognizes two distinct developmentally regulated cell surface antigens, with molecular masses of 170,000 and 140,000 daltons, in embryonic chick neural retina (Cole, G. J., and Glaser, L. (1984) Proc. Natl. Acad. Sci. U. S. A., in press). In vitro, the 170,000-dalton polypeptide is released by retinal cells into the surrounding culture medium and is present in material sedimentable at 100,000 X g. This pelletable material contains particles designated as adherons (Schubert, D., LaCorbiere, M., Klier, F. G., and Birdwell, G. (1983) J. Cell Biol. 96, 990-998) which promote cell-substratum adhesion of chick neural retina cells. In the present study, evidence is provided that the C1H3 monoclonal antibody inhibits cell adhesion to adheron-coated dishes when bound either to cells or to the adherons. The failure of other monoclonal antibodies, that bind to retinal cells with equal abundance, to disrupt adhesion demonstrates that the effect is specific. These data suggest that the neural-specific 170,000-dalton C1H3 polypeptide is the neural cell-adhesion molecule which is responsible for the ability of adherons to bind to cells.