The development of cell polarity involves virtually every aspect of cell biology. Yeast are less complex than cells traditionally used for studies on cell polarity and are amendable to sophisticated genetic analysis. This has resulted in a growing number of molecular markers for yeast cell polarity and an increasingly well-defined progression of molecular events required for bud formation. Together, these factors provide a favorable context in which to understand how the interplay between a large number of processes can polarize a cell. Many genes required for morphogenesis have been identified, and genetic interactions provide evidence that the products of these genes function together. Studies on cell polarity development in S. cerevisiae have demonstrated a requirement for small GTP-binding proteins and have established functional relationships between temporally coincident events. With the continued identification and analysis of genes required for morphogenesis, and the pursuit of these studies on a cytological and biochemical level, studies on yeast will continue to contribute to our understanding of cell polarity development.