The idea of using cellulosic biomass for producing ethanol fuel was born in the 1970s. Now the technologies required for cellulosic ethanol production have largely being developed. Cellulosic ethanol becomes the favorite clean renewable fuel also because cellulosic biomass is abundantly available and more than 75% cellulosic biomass can be converted to fermentable sugars. The amount of sugars recovered from cellulosic biomass in the US and worldwide could produce sufficient ethanol for world’s transportation needs. Although the Saccharomyces yeast was counted on as the microorganism to convert the cellulosic sugars to ethanol in the beginning, it was found that there were two major sugars, glucose and xylose, present in all types of cellulosic biomass. Unfortunately, the Saccharomyces yeast was found unable to utilize xylose for growth and to ferment xylose to ethanol. In this presentation, I will review how we overcame the serious barriers to make the yeast co-ferment glucose/xylose to ethanol and how our fundamental approaches as well as our subsequent work for developing the recombinant yeast had made it possible for a plant using our yeast to produce cellulosic ethanol since April 2004. This and other exciting undertakings have demonstrated that there are no serious obstacles for industry to use our yeast to produce cellulosic ethanol. In addition, I will also report how our yeast can be further improved for more cost-effective industrial cellulosic ethanol production in a few short years.