Recent evidence indicates that B cells are instructed continuously by B-cell receptor (BCR) signals to make crucial cell-fate decisions at several checkpoints during their development. Targeted disruption of BCR signalling components leads to distinct blocks in B-cell maturation, which indicates that key kinases and adaptors fine-tune BCR signalling to direct appropriate cell fates. Recent progress in unravelling the molecular mechanisms of the BCR signalling pathways has helped to clarify how BCR signals regulate the proliferation, survival and apoptosis of developing B cells.