Ye Luo, Ph.D. a* Louise C. Hawkley, Ph.D. b Linda J. Waite, Ph.D. c John T. Cacioppo, Ph.D. b Running Head: Loneliness, Health, and Mortality in Old Age a Department of Sociology & Anthropology, Clemson University, Clemson, South Carolina, USA b Department of Psychology and Center for Cognitive and Social Neuroscience, University of Chicago, Chicago, USA c Department of Sociology and Center on Aging, University of Chicago, Chicago, Illinois, USA This research was supported by Grant R01-AG036433-01 and R01-AG034052 from the National Institute on Aging. * Corresponding author: Department of Sociology & Anthropology, Clemson University, Clemson, SC 29634, USA. Tel.: +1 864 656 4209l fax +1 864-656-1252. : yel@clemson.edu (Y. Luo).