In this essay we argue that our societal and individual beliefs about aging can have an influence on the aging process. We give a brief illustration how life-span developmental theories have undergone a process of development themselves in the last years. Hereby it is essential that old age is conceptualized as a result of a lifelong aging process that can be influenced by individual action. Finally, we illustrate how developmental science can contribute to research on aging and on old age and discuss a number of research desiderata.