Mesenchymal stem cells, harvested from adult bone marrow, are promising in the field of regenerative medicine because of the vast differentiation potential into various cell lines such as: osteoblasts, chondrocytes, adipocytes, and neurons. Osteogenic differentiation of human mesenchymal stem cells (hMSC) could be an important tool in the treatment of orthopedic deficiencies such as bone defects. The extent of in vitro human mesenchymal stem cell growth, adhesion, motility and differentiation into osteoblasts is a function of the material surface chemistry which is mediated by protein adsorption onto the surface. A library of tyrosine derived polycarbonates allows the tailoring of material properties to suit specific cell response by varying the structure of the polymer at the pendent chain and the incorporation of PEG in the backbone. Increasing pendent chain length increases the hydrophobicity of the surface which is hypothesized to support osteogenic differentiation at a greater extent than hydrophilic surfaces. To determine the extent of osteogenic differentiation on thin films, cell morphology, cell proliferation, biochemical assays specific for osteoblasts, cytoskeletal arrangement and cell motility were assessed. The results of this study show that increasing the pendent chain length does not cause statistically significant changes in osteogenic differentiation, however the incorporation of polyethylene glycol in the polycarbonate backbone had a profound affect on cell morphology, proliferation and mineralization.