Recent evidence demonstrates that normal prostate tissue contains stem cells. There is also accumulating evidence that prostate cancer contains a population of cells with stem cell-like characteristics referred to as cancer stem cells, or tumor initiating cells. Both the normal prostate stem cell and cancer stem cell populations have important implications for the generation, therapeutic targeting, and prevention of prostate cancer. The purpose of this book is to explore the role of stem cells in prostate cancer, which is becoming an increasingly hot trend in cancer research.