Photopolymerizable polyethylene glycol (PEG) derivatives have been investigated as hydrogel tissue engineering scaffolds. These materials have been modified with bioactive peptides in order to create materials that mimic some of the properties of the natural extracellular matrix (ECM). The PEG derivatives with proteolytically degradable peptides in their backbone have been used to form hydrogels that are degraded by enzymes involved in cell migration, such as collagenase and elastase. Cell adhesive peptides, such as the peptide RGD, have been grafted into photopolymerized hydrogels to achieve biospecific cell adhesion. Cells seeded homogeneously in the hydrogels during photopolymerization remain viable, proliferate, and produce ECM proteins. Cells can also migrate through hydrogels that contain both proteolytically degradable and cell adhesive peptides. The biological activities of these materials can be tailored to meet the requirements of a given tissue engineering application by creating a mixture of various bioactive PEG derivatives prior to photopolymerization.