Lis Nielsen is Chief of the National Institute on Aging’s (NIA) Individual Behavioral Processes Branch, which supports behavioral, psychological and integrative biobehavioral research on the mechanistic pathways linking social and behavioral factors to health in mid-life and older age. This Branch examines aging processes across the full life course, including early life influences on later life outcomes, as well as research on behavioral and social processes in midlife that play a causal role in shaping trajectories of aging. Nielsen manages the Psychological Development and Integrative Science portfolio, which supports transdisciplinary research in affective science, health psychology, life-span developmental psychology, neuroeconomics and social neuroscience. She coordinates NIA research initiatives on midlife reversibility of risk associated with early life adversity, conscientiousness and healthy aging, socioemotional influences on decision-making, subjective well-being, and stress measurement. She serves on the Implementation Team for the trans-NIH Science of Behavior Change (SOBC) Common Fund Program, which promotes a mechanisms-focused experimental medicine approach to behavior change intervention design. Nielsen is the Project Scientist on the Midlife in the United States (MIDUS) Study, an NIA-funded national longitudinal study of health and well-being. She has a BA in Philosophy from Rhodes College, MA in Psychology (cand. Psych.) from the University of Copenhagen, and a PhD in Cognitive Psychology and Cognitive Science from the University of Arizona. She held an NIA-funded NRSA Post-Doctoral Fellowship in Psychology of Aging at Stanford University. Her scientific interests and research lie at the intersection of affective science and aging research.