The nuclear factor kappa enhancer binding protein (NF-kappaB) family of transcription factors regulates the expression of a large array of genes involved in diverse cellular processes including inflammation, immunity and cell survival. Activation of NF-kappaB requires ubiquitination, a highly conserved and versatile modification that can regulate cell signaling through both proteasome dependent and independent mechanisms. Studies in the past few years have provided new insights into the mechanisms underlying regulation of NF-kappaB by ubiquitination, including the involvement of multiple linkages of ubiquitin, the essential role of ubiquitin binding, and the function of unanchored polyubiquitin chains. In this review, we will focus on recent advances in understanding the role of ubiquitination in NF-kappaB regulation in various pathways.