The past two decades have witnessed an enormous progress in our understanding of plastid (chloroplast) biology. Basic principles of plastid biogenesis, genome structure and function, gene expression and its regulation as well as plastid-nuclear interaction and communication pathways have been elucidated. In addition, the possibility to directly alter the genetic information of the plastid by transformation has facilitated the study of virtually all aspects of plastid biology in vivo and, moreover, has paved the way to diverse applications of transgenic plastids in biotechnology. The present book provides a comprehensive overview of our current knowledge on plastid biogenesis, plastid-nuclear communication, the regulation of plastid gene expression at all levels, and also assesses the state of the art in key technologies, such as proteomics and chloroplast transformation. Written by recognized experts in the field, it covers plastid differentiation and division, genome structure and function, plastid inheritance, recombination, DNA replication and repair, transcription, RNA processing and translation as well as crucial posttranslational processes in plastid biogenesis and function, including protein processing, the assembly of multiprotein complexes, protein stability and degradation, protein import and sorting.