Publisher Summary Sporulation in both eukaryotic and prokaryotic organisms is one of the simplest developmental processes accessible to experimentation. Morphological and physiological changes take place n both eukaryotic and prokaryotic organisms. Studies on sporulation in simple eukaryotic microorganisms provide an attractive system for comparison with bacteria. Among these, there has been an increasing interest in sporulation in Saccharomyces cerevisiae. Sporulation in yeast leads, on the one hand, to the production of semidormant spores, but on the other hand introduces the process of meiosis. The chapter describes the life cycle of Saccharomyces cerevisiae. In its stable form, this yeast is diploid in the vegetative phase. The morphological changes during sporulation are discussed in the chapter. With the light microscope, one can detect only the most generalized changes in nuclear organization during meiosis. At present, the studies with yeast are in a more preliminary stage, but have already suggested a related series of stages based on the morphological changes in the nucleus.