As I reflect on the evolution of this book, I am struck by the differences be tween my early conceptions and the final product. When I was first ap proached by Springer-Verlag regarding a monograph on my interests in the area of fetal lung development, I imagined that it would be relatively easy to summarize my contributions, plus the work of other investigators as needed for proper perspective. This rather naive idea was abandoned as I prepared my initial outlines for the monograph. I quickly realized that con tributions from my laboratory are not sufficient for telling the story of "hormones and lung maturation." The result of this decision is a longer and more heavily-referenced book than I originally envisioned. Although I have attempted to discuss in considerable detail most aspects of hormones and the fetal lung, I know with certainty that I have not in cluded all relevant references in each area. In most of these instances this reflects my impatience or lack of diligence, and I offer my apologies to those investigators whose work has been so omitted. In some situations published work has not been cited in a deliberate decision to limit the breadth of discussion or, rarely, due to my judgment of major shortcom ings in experimental design or execution."