Micrometeorites played an essential role in the formation of the atmosphere of the Early Earth and also served as a significant source of activation for organic prebiotic chemistry on mineral surfaces. The present book gives a coherent account of this scenario, embedding the more specific results within a broader framework that considers the creation and evolution of the Early Earth. It thus addresses students and nonspecialist researchers in the fields of planetary atmospheres, biogeophysics and astrobiology. The experienced researcher will find this volume to be a modern and compact reference, as well as a source of material for lectures in this field. TOC:Staging the Cosmic Theater.- Primitive Extraterrestial Matter on Earth.- Formation of the Earth's Atmosphere.- Exobiology with Unmelted Micrometeorites.- Micrometeoritic "Ashes" in Exobiology and Early Climatology.- Micrometeorites in Comparative Planetology.- Parent Bodies of Micrometeorites and Early Solar System Processes.- Other Challenges Ahead.- Summary and Prospects.