PROJECT SUMMARY This application responds to PA-20-272 Administrative Supplements to Existing NIH Grants and Cooperative Agreements (Parent Admin Supp Clinical Trial Optional). It will make significant contributions to Intensive Longitudinal Health Behavior Network (ILHBN) cross-study projects by (1) sharing relevant data collected through the TIME study to support four cross-network projects as well as future work with shared datasets, and (2) leading the effort on a cross-network project to investigate reliability and variance in affect data collected across ILHBN studies. To date, the ILHBN has collectively generated rich intensive longitudinal data (ILD) and explored state-of-the-art methodologies for analysis of such health data. However, data sharing across and outside of individual projects remains limited due to budgetary and personnel constraints that prevent some sites from preparing their data to share within the ILHBN, as well as the additional challenges brought on by the pandemic that have required each team to focus more effort than anticipated on their own data collection. The richness of the ILD collected means that there are many possibilities for secondary analyses and modeling efforts that are beyond the scopes of the parent projects if data harmonization and sharing can be achieved across the projects. The projected sample size across all studies is 2210 participants and 854,220 person days across all sites. This is an unprecedented dataset that could support a large body of future work on the use of ILD for behavioral measurement, including important methodological results about how this new field might move forward. Gaps in knowledge about optimal ways to measure to better understand affect dynamics can be filled by pooled analysis from our network. Improving methodologies to capture dynamic emotional experiences in naturalistic settings can help researchers elucidate the affective processes underlying various behaviors and disorders. This proposed administrative supplement offers a unique opportunity to contribute to cross network projects examining a variety of impactful questions about longitudinal changes in health behavior and makes contributions to improved understanding of the psychometric properties of affect items measured through EMA across many occasions.