In a tribute to Dr. Karl on his eighty-fifth birthday the authors write about his character traits and about the salient events of his impressively productive life to date. Included are his early interest in mental health during medical school, the encouragement he received from his close relationship with his educator-physician father in establishing jointly the Menninger Foundation, the development of his independent lines of thought, and his wide-ranging interests in child care, psychoanalysis, conservation, education, and administration. His major writings over the years are briefly mentioned as are his still active current interests.