Colorectal cancer is the third-leading cause of cancer related mortality in the United States. The intricate molecular mechanisms involved in the regenerative process of the normal intestine and the identity of putative somatic intestinal stem cells have become clear. In parallel with this, experiment evidence has emerged supporting the century old hypothesis that solid tumor initiation, progression, chemoresistance and recurrence is the result of a small population of cancer cells with self-renewal and pluripotency capabilities. These "cancer stem cells" (CSCs) present a unique opportunity to better understand the biology of solid tumors in general, as well as targets for future therapeutics. In this review, we will summarize the current understanding of intestinal stem cell biology and translate it to colorectal CSCs to provide a basis for understanding chemoresistance, cancer recurrence and metastasis. A more complete understanding of the biology of colorectal CSCs will translate into the development of better chemotherapeutic and biological agents for the treatment of colorectal cancer.