A number of prominent demographers have recently reiterated the argument that a lasting mortality decline is a key determinant of the fertility transition. Of the main hypothesized pathways linking fertility to mortality, the one least studied is the insurance hypothesis: the notion that, in high-mortality contexts, people decide to have more children in order to anticipate possible future child deaths and lessen the risks of having too few surviving offspring. In-depth interviews and focus groups from Zimbabwe and Senegal are used to examine this hypothesis and to extend it into a broader theory of reproductive decision making under uncertainty. Whereas insurance strategies are frequent in Zimbabwe and occur in urban Senegal, in the higher-mortality settings—the rural Senegalese site and the recent past described by respondents in Zimbabwe and urban Senegal—deliberate fertility-limitation strategies are rare. The data depict fundamental changes in attitudes, strategies, and behaviors concerning family size over time and, in Senegal, over space. Important reproductive goals and risks extend far beyond numbers of children and mortality. Parents seek to have healthy, successful children for many reasons including companionship, descendants, and old-age support. Diverse investments in child quality (their education, health, etc.) and quantity (numbers of births) are the main means to attain these goals and, less recognized by demographers, are also important ways for parents to manage uncertainty in family-building outcomes; the “classic” insurance mechanism is only one, often minor, aspect of the quantity option.