The transcription factor nuclear factor-kappaB (NF-kappaB) contributes to many events in the immune system. Characterization of NF-kappaB has facilitated our understanding of immune cell differentiation, survival, proliferation, and effector functions. Intense research continues to elucidate the role of NF-kappaB, which is shared in several receptor signaling pathways, such as Toll-like receptors, the tumor necrosis factor receptor, and antigen receptors. The specificity of cellular responses emanating from stimulation of these receptors is determined by post-translational modification, or 'fine tuning', which regulates spatiotemporal dynamics of downstream signaling. Understanding the fine tuning mechanisms of NF-kappaB activation is crucial for insights into biological regulation and for understanding how cellular signaling pathways are tightly regulated to guide different cell fates. In this review, we focus on recent advances that illuminate the fine tuning mechanisms of NF-kappaB activation by BCR signaling and have increased our comprehension of complex signal systems.