Important cellular characteristics, including selective adhesion, growth rate, motility, and differentiation, are controlled, in part, by signals received at the cell surface. The molecular mechanisms for the cell surface control of these cell behaviors are largely unknown. In order to probe the role of specific extracellular molecules in controlling cell function, we report the development of synthetic surfaces which generally support the long-term growth of cells yet can be readily derivatized with a wide variety of molecules of biological interest. Polyacrylamide gels containing a gradient of active ester groups were prepared and then the esters were displaced with ligands to generate a gradient of carboxylic acid, tertiary amine, or hydroxyl groups. When untransformed mouse fibroblasts (BALB/3T3) were seeded on the various surfaces, they attached and grew only on those derivatized with carboxylic acids or hydroxyl groups within narrow concentration ranges. Cell growth rate, density, and morphology on polyacrylamide gels containing the optimal concentration of carboxylic acid groups (approximately 30 mumol/ml) were comparable to those on tissue culture plastic, whereas growth on hydroxyl group-derivatized gels was less extensive. In contrast, short-term (90-min) adhesion to hydroxyl group-derivatized gels was greater than that to carboxylic acid-derivatized gels. Both short-term adhesion and long-term growth required serum. Growth-supportive polyacrylamide gels were readily derivatized with molecules of biological interest. The techniques reported here are applicable to other types of cell in culture since the nature and concentration of substratum functional groups can be easily varied and tested for support of long-term cell growth.