Prior to pursuing higher degrees, I was both concerned and fascinated about the world population explosion or population bomb. My naive assumption was that fertility drove this trend. Exposure to demographic transition “theory,” through graduate studies in demography, led me to realize that it was actually the secular ( long-term) mortality decline which stimulated the explosive population growth. Subsequent studies in epidemiology enabled me to appreciate the overlap between demography and epidemiology, and recognize more fully that Abdel Omran’s Theory of Epidemiologic Transition derives from, and extends demographic transition theory.