Extracellular matrix (ECM) proteins are established regulators of granulosa cell survival, morphology, and differentiation. In this study, the roles of ECM adhesion peptide density on murine granulosa cell adhesion, morphology, and steroid secretion were probed using synthetic matrices. The synthetic matrix was fabricated from the polysaccharide alginate, which does not inherently support cell adhesion but can be modified with controlled densities of adhesion peptides (10 −4 to 2×10 −1 ng/cm 2). GRM02, a murine granulosa cell line, and primary murine granulosa cells were cultured on alginate matrices modified by coupling of synthetic peptide sequences containing the Arg–Gly–Asp motif common to ECM proteins. Cells cultured on these peptide-modified surfaces (0.02, 0.2 ng/cm 2) attached and spread, with morphologies specific to the peptide identity and density. Additionally, progesterone and estradiol secretion was a function of peptide density, with up to threefold increases compared to controls. These results indicate that the density and identity of adhesion peptides regulate granulosa cell function. This system provides a mechanism to examine the granulosa cell-ECM interactions that occur during follicle maturation.