[Figure: see text] ▪ Abstract  This perspective tells the story of the discovery, characterization, and understanding of the surfactant system of the lung; of how investigators from many disciplines studied the system, stimulated by the demonstration of surfactant deficiency in respiratory distress syndrome of the newborn; and of how the resulting knowledge formed a basis for highly successful surfactant substitution treatment for this syndrome. The chapter includes personal reminiscences and reflections of the author and ends with a few thoughts about the present status and future prospects of this field of research.