This chapter examines areas of knowledge where the Romans displayed expertise and consciously sought to develop techniques and systems that enabled them to better understand and control future uncertainties. It begins by looking at architecture, military logistics and law, before moving on to aspects of financial management, such as maritime loans, interest rates and annuities; it then finishes by looking at the probabilistic thinking involved in the religious practices of oracle and dream interpretation. It argues that the ancients did not rely solely on religion to deal with uncertainty. The Romans thought systematically and creatively about many areas where future uncertainty could be assessed and managed. These approaches were not statistical but all show an awareness of a range of likelihoods and possibilities. The Romans did not have statistical models, nor had they worked out how to calculate probabilities, but they did develop a range of sophisticated ways of dealing with the many unknowns they faced.