Stem Cells are unique in that they have the potential to develop into many different cell types in the body, including brain cells, but they also retain the ability to produce more stem cells, a process termed self renewal. There are multiple types of stem cell, such as embryonic stem (ES) cells, induced pluripotent stem (iPS) cells, and adult or somatic stem cells. While various stem cells can share similar properties there are differences as well. For example, ES cells are able to differentiate into any type of cell, whereas adult stem cells are more restricted in their potential. The promise of all stem cells for use in future therapies is exciting, but significant technical hurdles remain that will only be overcome through years of intensive research. Due to the limitations of pharmacological and other current therapeutic strategies, stem cell therapies have emerged as promising options for treating many incurable neurologic diseases. A variety of stem cells including pluripotent stem cells (i.e., embryonic stem cells and induced pluripotent stem cells) and multipotent adult stem cells (i.e., fetal brain tissue, neural stem cells, and mesenchymal stem cells from various sources) have been explored as therapeutic options for treating many neurologic diseases, and it is becoming obvious that each type of stem cell has pros and cons as a source for cell therapy.