The nuclear factor-kappa B (NF-κB) family of transcription factors has recently emerged as a major regulator of the growth and elaboration of neural processes. NF-κB signaling has been implicated in controlling axon initiation, elongation, guidance and branching and in regulating dendrite arbor size and complexity during development and dendritic spine density in the adult. NF-κB is activated by a variety of extracellular signals, and either promotes or inhibits growth depending on the phosphorylation status of the p65 NF-κB subunit. These novel roles for NF-κB, together with recent evidence implicating NF-κB in the regulation of neurogenesis in the embryo and adult, have important implications for neural development and for learning and memory in the mature nervous system.