Human embryonic stem cells (hESCs) have the potential to treat many illnesses such as Parkinson’s disease, spinal cord injuries, diabetes, and cardiac diseases. To make these therapies a reality, a large number of undifferentiated hESCs are needed. However, a major obstacle to large scale production and use of hESCs is that the culture conditions, both the substrate and the soluble factors, are poorly defined. In this thesis, two completely synthetic polymer networks: a semi-interpenetrating polymer network (sIPN) and an interpenetrating polymer network (IPN), were developed to support hESC adhesion and growth. The sIPN and the IPN were developed to act as extracellular matrix (ECM) support for hESCs. To identify the parameters for designing the sIPN and the IPN, the cell adhesion receptors of hESCs were characterized using flow cytometry and immunocytochemistry. The α₂β₁, α₆β₁, and αᵥβ₃ integrins were identified as the most important integrins for HI adhesion to the culture surface. Targeting these integrins, synthetic peptides were designed as cell adhesion ligands. The hESCs were initially cultured on sIPNs, which were designed to replace the ECM components of mouse embryonic feeders, on which hESCs are typically cultured. The sIPN consisted of poly(N-isopropylacrylamide-co-acrylic acid) that was loosely crosslinked by enzymatically degradable peptide crosslinker Gln-Pro-Gln-Gly-Leu-Ala-Lys-NPE. Linear p(AAc) chains (MW 450,000) were modified with the synthetic peptide (AcCGGNGEPRGDTYRAY-NH₂) (bsp-RGD(15)). This Arg-Gly-Asp motif represents an active site in a number of extracellular proteins and binds to several integrin receptors. The HSF- 6 cells, an hESC line, were able to adhere to the sIPN, were viable, exhibited morphologies of undifferentiated cells, and stained positive for the hESC markers OCT-4 and S SEA-4. Subsequent experiments explored using the IPN as the artificial ECM, since the IPN is easier for scale-up and is more amendable to high-throughput experimentation. A poly(acrylamide-co-ethylene glycol/acrylic acid) IPN was functionalized with peptides that served as adhesion ligand for engagement with either the α₂β₁, α₆β₁, or αᵥβ₃ integrins. Those peptides were functionalized with a coupling density of 20 μM which corresponded to a peptide surface density of 15 pmol/cm². The HI hESCs were cultured in defined media conditions consisting of X-VIVO media + 80 ng/mL hbFGF + 0.5 ng/ml TGF-pimedia. IPNs functionalized with bsp-RGD(15) were able to support HI cells for multiple passages. The HI cells cultured on bsp-RGD(15), lam-RGD(lO), and c(lamRGD)(9) stained positive for hESC markers OCT-4, SSEA-4, and TRA-1-60. However, over several passages, the colony morphology became multilayerd and many of the colonies lifted from the surface. In addition, the stromal cells proliferated faster than the colonies and outgrew the culture on all surfaces. Surprisingly, the HI cells cultured on non-RGD peptide surfaces exhibited poor adhesion. Assessment of the secretion of ECM proteins found that HI cells cultured on Matrigel™ synthesized Collagen I, Collagen IV and laminin, but not fibronectin and vitronectin. In contrast, the HI cells cultured on bspRGD(15), lam-RGD(lO), and c(lam-RGD)(9) IPN surfaces were positive for Collagen I, Collagen IV, fibronectin and laminin, but not vitronectin. Another important finding was that the IPN surface was too “non-fouling” to permit ECM protein deposition beyond the colony borders. Future work will address designing a polymer that is less non-fouling, so that the hESCs can remodel the ECM environment after initial adhesion.