This chapter provides an overview of the U.S. Food and Drug Administration (FDA) review process for cancer gene therapy products. Cancer gene therapy products are reviewed within FDA’s Center for Biologics Evaluation and Research (CBER). Although there are currently no FDA-approved gene therapies, CBER works with academic and industry sponsors during all stages of product development. CBER’s roles range from giving scientific advice to providing regulatory oversight to ensure the appropriate and safe treatment of human subjects. CBER teams composed of experts in various disciplines (chemistry/manufacturing/controls, pharmacology/toxicology, clinical, biostatistics, and regulatory project managers) review product and manufacturing issues, preclinical assessment, and clinical trial design at all stages of product development. This chapter summarizes CBER’s functions and highlights some issues that are of particular importance for sponsors of cancer gene therapy trials. References with further regulatory guidance and information are provided.