The E2F gene family of transcription factors is a regulator of the G1 to S phase transition of the mammalian cell cycle. This volume details which cellular genes are thought to be regulated by E2F and describes models for E2F action based on protein-protein complexes that either positively or negatively influence cell growth. Also documented are the effects of altered E2F activity, achieved either by viral transformation or overexpression of E2F family members. Finally, a comparison is provided between E2F and cell cycle regulators from yeast, in the hopes that parallels can be drawn that will provide insight into G1/S-phase specific transcription in mammalian cells. The last several years have seen tremendous growth in our knowledge of this gene family. This volume synthesizes what is known about E2F and provides researchers with a solid foundation for future investigations.