Signaling by the Wnt family of secreted glycolipoproteins via the transcriptional coactivator beta-catenin controls embryonic development and adult homeostasis. Here we review recent progress in this so-called canonical Wnt signaling pathway. We discuss Wnt ligands, agonists, and antagonists, and their interactions with Wnt receptors. We also dissect critical events that regulate beta-catenin stability, from Wnt receptors to the cytoplasmic beta-catenin destruction complex, and nuclear machinery that mediates beta-catenin-dependent transcription. Finally, we highlight some key aspects of Wnt/beta-catenin signaling in human diseases including congenital malformations, cancer, and osteoporosis, and discuss potential therapeutic implications.