Americans of low socioeconomic status (SES) are less healthy than those of high SES. Understanding the causes of these health disparities is one of the most important research questions social scientists face today. I propose to investigate an understudied cause of such health disparities: economic uncertainty. Income volatility has been rising in the US, making it an increasingly important source of economic uncertainty. For 92 percent of Americans, having financial stability is more important than moving up the income ladder. The income swings are often unpredictable, making them impossible for families to anticipate and prepare accordingly. When income dips, low-SES families, who often lack a cushion of savings, may struggle to make ends meet. The prospect of this scenario of financial distress may cause anxiety, worry, and stress. The anticipation and concern about an aversive and uncertain event can cause anxiety and worry while the uncertainty about how one might cope if the event occurs may cause stress. According to the allostatic load framework, the stress increases the risks of cardiovascular disease and of age-related metabolic diseases, promotes cognitive decline and dementia, and accelerates cellular aging. I propose to analyze the relationship between income volatility, psychological health, and physiological aging. This project is interdisciplinary. I am an economist and can analyse and measure income volatility. However, I lack the skills to conceptualize and measure anxiety, worry, and stress; to understand the biological processes through which uncertainty and stress may accelerate aging; and to know how to use biomarkers to measure physiological aging. The K01 will provide training – under the guidance of two outstanding mentors and an expert advisory committee – that will give me such skills. My mentors, Profs. Arthur Stone and Eileen Crimmins, are leading experts in the areas where I need training and have experience in mentoring K01 awardees. The award will provide protected time for me to develop this agenda. The specific aims of this proposal are to: 1) Measure the extent of income volatility and document how it is distributed in the population. 2) Investigate the relationship between income volatility and psychological health. 3) Examine the relationship between income volatility and physiological aging. 4) Study populations at risk, such as those without a buffer of savings. My long-term career goal is to become an expert on how economic uncertainty affects health and aging. I am confident that this sustained period of career development and training will enable me to launch an independent research career and emerge as a leading researcher in this area.