Human mesenchymal stromal cell (hMSC) behavior can be modulated by a combination of extracellular biochemical and mechanical signals. We use polydimethylsiloxane (PDMS) as a mechanically-tunable, viscoelastic cell culture substratum to mimic the native extracellular microenvironment of hMSCs. Using protein functionalization, we can also alter the surface chemistry of the cell culture environment. The interplay between surface chemistry and substrate stiffness, however, is not well understood. The hMSCs not only actively deform the elastomeric substrata, but are also able alter their subsequent biological response. Here, we explore how hMSC morphology, gene expression, and differentiation can be altered by substrate viscoelastic properties along with protein functionalization to try and decouple these two effects.