Neural progenitor cells have tremendous utility for understanding basic developmental processes, disease modeling, and therapeutic intervention. The protocols described in this unit provide detailed information to isolate and expand human and rodent neural progenitor cells in culture for several months as floating aggregates (termed neurospheres) or plated cultures. Detailed protocols for cryopreservation, neural differentiation, exogenous gene expression using lentivirus, and transplantation into the rodent nervous system are also described.