Prior to her current position, Zajacova was a National Institute on Aging Postdoctoral Fellow at the Population Studies Center and an affiliate at the Center for Social Epidemiology and Population Health at the University of Michigan from 2007-2009. She was also an affiliate at the Population Research Center and a lecturer in the Mathematics Department at the University of Texas at Austin in 2006-2007. Zajacova received a Ph.D. in Sociology and Demography from Princeton University in 2006. Her dissertation focused on socioeconomic determinants of health and mortality among U.S. adults. Her undergraduate degree is in Psychology, earned Summa cum Laude from Hunter College, City University of New York.