AbstractThe heartbeat is initiated and coordinated by a heterogeneous set of tissues, collectively referred to as the pacemaking and conduction system (PCS). While the structural and physiological properties of these specialized tissues has been studied for more than a century, distinct new insights have emerged in recent years. The tools of molecular biology and the lessons of modern embryology are beginning to uncover the mechanisms governing induction, patterning and developmental integration of the PCS. In particular, significant advances have been made in understanding the developmental biology of the fast conduction network in the ventricles – the His‐Purkinje system. Although this progress has largely been made by using animal models such as the chick and mouse, the insights gained may help explain cardiac disease in humans, as well as lead to new treatment strategies. Birth Defects Research (Part C) 69:46–57, 2003. © 2003 Wiley‐Liss, Inc.