Proteins and enzymes have a vast scope of applications in several aspects of our life like in detergents, leather, paper and pulp, textile, cosmetic, healthcare and food processing industries, for clinical and diagnostics research. Due to the wide uses of proteins and enzymes interest in the industrial production of such useful enzymes has grown up in recent years. Today the focus is on developing efficient purification methods for proteins which can meet the increasing industrial needs. A number of separation and purification strategies have been developed for these purposes including non chromatographic methods and also some modern methods including chromatographic techniques. This work aims to develop such an efficient method for the purification of biochemically important enzyme, Alcohol Dehydrogenase from yeast cells. Three phase partitioning is a useful affinity based non chromatographic method to purify proteins and enzyme which is applied to purify the enzyme ADH. This book will be proved useful for researchers, students, individuals and anyone working in the area of protein purification.