This volume includes timely reviews of several aspects of chromatin biology written by scientists at the forefront of this rapidly moving field. Topics covered include the structure and function of protein modules within chromatin-remodeling proteins, newly characterized histone modifications (methylation, ubiquitylation) and their functional consequences, transcription and histone dynamics, roles of chromatin remodeling factors in DNA replication and repair, and current models of nucleosome-remodeling mechanisms.