Developmental cardiology is finally coming of age. The field was sparsely populated in the past by relatively few investigators interested in understanding how and why the fetal and newborn heart differs from the mature heart. Most earlier studies were largely descriptive, but a relatively large body of work accumulated over approximately two decades to describe some of the physiological, functional, pharmacological, biochemical and morphological aspects of normal cardiac development. This time period represented the infancy and childhood of the emerging field of cardiac development. The natural progression from childhood to adulthood involves a tumultuous period of maturation (adolescence) which is characterized largely as a struggle for identity and independence. However, adolescence is also a time of exploration, overwhelming excitement and unparalleled growth. That the rapid growth phase of developmental cardiology is already upon us is evidenced by the response to the call for papers for this Spotlight Issue. We anticipate that during the next decade, developmental cardiology will exhibit many of the other features that define adolescence. Recent advances in molecular genetics and cell biology have fostered renewed interest in normal and abnormal aspects of cardiac development and maturation. It is reasonable to expect that this new level of interest and participation will soon result in answers to some of the very basic biological questions related to cardiac development and maturation. During cardiogenesis, the vertebrate heart undergoes a rapid transformation from a straight heart tube to a complex four-chambered pump which maintains the systemic and pulmonary circulations in series. Until recently, the processes controlling this exquisitely complex and tightly regulated transformation represented mysteries with few clues. Similarity, the subsequent maturation of the heart, maintenance of a terminally differentiated state and the molecular aspects of responses to a variety of pathophysiological states were seemingly beyond our understanding. By applying lessons learned using a number of different species, model systems and investigative techniques, the characterization of these fundamental biological processes is now within our grasp. Continued advancement will be dependent upon maintaining cross-fertilization among investigators involved in a variety of disciplines. It is impossible to cover all aspects of this rapidly growing field comprehensively in a single issue of the Journal. We hope that this compilation of brief reviews and original articles will not only enlighten, but also stimulate the sharing of knowledge and ideas that is necessary to sustain future progress. We are poised at the threshold of a new era in our understanding of the regulation of myocardial form and function. The potential for future applications of this new knowledge is limited only by our collective vision. This Spotlight Issue was informally conceived in May 1993 over dinner in London with Professor David Hearse and two associate editors from the previous editorial board, Drs. William Coetzee and Metin Avkiran. We are especially grateful to Professor Hearse in finalizing the plans for this issue. Dr. Frank Kelly initially took on the project as associate editor and was a major force in getting us underway. With the subsequent change in editorial boards, we as guest editors had the pleasure of working also with members of the new editorial board, particularly Michiel Janse and Tobias Opthof.