Dr. Leon E. Rosenberg delivered the following presentation as the Grover Powers Lecturer on May 14, 2014, which served as the focal point of his return to his "adult home" as a Visiting Professor in the Department of Pediatrics. Grover F. Powers, MD, was one of the most influential figures in American Pediatrics and certainly the leader who created the modern Department of Pediatrics at Yale when he was recruited in 1921 from Johns Hopkins and then served as its second chairman from 1927 to 1951. Dr. Powers was an astute clinician and compassionate physician and fostered and shaped the careers of countless professors, chairs, and outstanding pediatricians throughout the country. This lectureship has continued yearly since it first honored Dr. Powers in 1956. The selection of Dr. Rosenberg for this honor recognizes his seminal role at Yale and throughout the world in the fostering and cultivating of the field of human genetics. Dr. Rosenberg served as the inaugural Chief of a joint Division of Medical Genetics in the Departments of Pediatrics and Internal Medicine; he became Chair when this attained Departmental status. Then he served as Dean of the Medical School from 1984 to 1991, before he became President of the Pharmaceutical Research Institute at Bristol-Myers Squibb and later Senior Molecular Biologist and Professor at Princeton University, until his recent retirement. Dr. Rosenberg has received numerous honors that include the Borden Award from the American Academy of Pediatrics, the McKusick Leadership Award from the American Society for Human Genetics, and election to the Institute of Medicine and the National Academy of Sciences.