This ongoing longitudinal project administered by the IOA follows behavioral, psychological, social, and biological aging of national samples of U.S. adults between the ages 25 and 74 at the time of recruitment. Many have been followed for nearly 30 years. This major study is funded by the National Institute on Aging and involves researchers from many universities throughout the United States. Originating in 1995 with 7,000 respondents, MIDUS is one of the first large-scale studies to link psychosocial and behavioral factors to health, including a comprehensive array of biological and neurological assessments. The MIDUS data are publicly available and are used by scientists from around the world to understand pathways to healthy aging. See the MIDUS website for information about accessing the public data, a database of academic publications using MIDUS data, and MIDUS newsletters that distill research results for the public. MIDUS is led by Carol Ryff, Ph.D., Director of the Institute on Aging.