This chapter provides a theoretical background on probabilistic reasoning and discusses the state-of-the-art application of subjective probability questions in surveys around the world. It describes measurement mechanisms for subjective probability questions with a special focus on the influence of cultural orientations pertinent to response patterns in these questions from the cross-cultural psychology literature. Probabilistic expectation questions, especially the questions on subjective life expectancy (SLE), have been used extensively in policy research. Focusing on the US data, racial/ethnic/linguistic groups were associated with distinctive heaping patterns when responding to the SLE question. The chapter examines SLE item nonresponse using Health and Retirement Study (HRS), English Longitudinal Study of Ageing (ELSA), and Survey of Health, Ageing and Retirement in Europe (SHARE) public-use data. ELSA and SHARE are modeled after HRS, and all three studies use a similar methodological approach.