In the past decade the dogma that we are born with a certain number of nerve cells and that the brain is incapable of generating new neurons and renewing itself has been proven incorrect. There is a renewal process in the adult brain, called neurogenesis, facilitated by the presence of neuronal stem cells. The capacity of olfactory receptor neurons to regenerate from a pool of multipotent stem cells highlights the olfactory neuroepithelium as an important source of adult neuronal stem cells. The olfactory stem cell has the undeniable advantage that it can be easily used for autologous transplantation to avoid graft versus host reactions. Once this is achieved new promising therapeutic venues for the treatment of various neurological diseases can be put into practice. While the regenerative capacity of the olfactory neuroepithelium has been well studied less is known about the molecular events controlling adult olfactory stem cell activity. Therefore this book sheds light on the isolation and characterisation of adult olfactory stem cells as well as molecular mechanisms involved in olfactory stem cell proliferation and differentiation.