Written and edited by experts in the field, this collection covers recent advances in our understanding of nuclear organization and function. The contributors discuss the 3D organization of chromatin, the various nuclear bodies and compartments that have been identified, and the roles of RNA and actin in shaping nuclear organization, as well as how these structures interact with each other and with peripheral features (e.g., the nuclear pore complex and inner nuclear membrane proteins) to carry out the work of the nucleus. Insights into DNA replication timing and RNA processing dynamics based on new technologies aimed at examining chromatin and other intranuclear structures at high resolution are also included.