ABSTRACT – DAILY DIARY PROJECT The objective of the MIDUS Daily Project is to determine how short term fluctuations in daily stress processes impact longer-term health and well-being throughout midlife and later adulthood. Specific aims are to: (1) Assess changes in multiple aspects of daily stressors and daily well-being across up to four occasions spanning up to 30 years and three historic periods; (2) Investigate how disrupted diurnal rhythms of salivary cortisol provide a physiological mechanism linking daily stress and health; and (3) Add tablet-based mobile assessments of daily experiences to the MIDUS protocol to enhance daily measurements of stress processes and capture unique assessments of cognitive health. These aims will be addressed by conducting additional waves of longitudinal data collection for the MIDUS Core and Refresher Daily projects. We will continue to use an 8-day telephone diary study of daily stressors and well-being combined with multiple assessments of saliva (4 occasions × 4 days) to obtain salivary cortisol. In addition, we will add a 14-day tablet data collection following the daily telephone survey. The MIDUS Daily project will continue to incorporate the rich sociodemographic, personality, and cognitive measures from other MIDUS projects in our analyses to study how they relate to changes in daily stress processes over up to 30 years. We will also use data from the gene expression, biomarker, and neuroscience projects to examine how changes in daily stress processes predict gene expression profiles and changes in various indicators of health (e.g., allostatic load, inflammatory processes, neuroendocrine regulation, cardiovascular risk).