This chapter considers the concept of perinatal programming (also called developmental origins of health and disease (DOHaD). The intent of the chapter is to spur interest in potential mechanisms and to act as a springboard for those who may be interested in embarking on studies that might lead to primordial prevention. Accordingly, the text presents the initial concepts, summarizes some of the key studies in both humans and animal models that have spurred interest and further research in the field, and discusses current thinking about the mechanisms.