Thisvolume details our current understanding of the architecture and signalingcapabilities of the B cell antigen receptor (BCR) in health and disease. Thefirst chapters review new insights into the assembly of BCR components andtheir organization on the cell surface. Subsequent contributions focus on themolecular interactions that connect the BCR with major intracellular signalingpathways such as Ca2+ mobilization, membrane phospholipidmetabolism, nuclear translocation of NF-kB orthe activation of Bruton's Tyrosine Kinase and MAP kinases. These elementsorchestrate cytoplasmic and nuclear responses as well as cytoskeleton dynamicsfor antigen internalization. Furthermore, a key mechanism of how B cellsremember their cognate antigen is discussed in detail. Altogether, the discoveriespresented provide a better understanding of B cell biology and help to explainsome B cell-mediated pathogenicities, like autoimmune phenomena or theformation of B cell tumors, while also paving the way for eventually combating thesediseases.