Findings over the past decade demonstrating persistent neurogenesis in the adult brain have overturned dogma, provoked reevaluation of cellular plasticity in the mature brain and raised hopes for novel approaches to brain repair. Recent discoveries reveal that neurogenesis is regulated by environmental stimuli and can be responsive to brain injury. This cellular plasticity may indicate a possible endogenous repair program. By understanding the mechanisms involved, it may be possible to harness this plasticity to recruit endogenous neural stem cells or to graft stem cells to achieve structural brain repair.