Biomaterials can potentially enhance the delivery of viral and nonviral vectors for both basic science and clinical applications.Vectors typically consist of nucleic acids (DNA, RNA) packaged with proteins, lipids, or cationic polymers, which facilitate cellular internalization and trafficking. These vectors can associate with biomaterials that support cell adhesion, a process we term substrate-mediated delivery. Substrate immobilization localizes the DNA and the delivery vector to the cellular microenvironment.The interaction between the vector and substrate must be appropriately balanced to mediate immobilization, yet allow for cellular internalization. Balancing the binding between the biomaterial and the vector is dependent upon the surface chemistries of the material and the vector, which can be designed to provide both specific (e.g., biotin–avidin, the strongest known noncovalent interaction between a protein and its ligand) and nonspecific (e.g., van der Waals) interactions. In this review, we describe the biomaterial and vector properties that mediate binding and gene transfer, identify potential applications, and present opportunities for further development.