PROJECT ABSTRACT The Rural Drug Addiction Research Center (RDAR) proposes the alteration and renovation of approximately 1,610 square feet of shell space on the third floor of the College of Business Administration (CBA) Building to create a state-of-the-art Longitudinal Networks Core (LNC). The CBA Building is centrally located on the city campus of the University of Nebraska-Lincoln (UNL) and will also house RDAR?s central administrative office, providing easy access to LNC by Center members. LNC will comprise three components adjacent to the Center: 1) a Secure Computer Facility to house RDAR?s Open Dynamic Interaction Network (ODIN) platform, LNC?s cutting-edge cohort tracking and retention software; 2) a mobile phone Research Laboratory, which will enable future modifications of the ODIN platform to include novel biomarker and quantified-self technologies; and 3) a Cohort Monitoring Room designed to provide researchers a flexible, interactive work space in which to process and visualize ODIN-collected data. LNC?s technology will enable long-term behavioral surveillance of users of methamphetamine and other illicit stimulants, opioids, and cocaine and its derivatives in the region, and data collected by LNC will support a range of drug use related research projects. Specifically, LNC will provide RDAR researchers with a subject pool that will participate in laboratory-based projects; context sensitive samples for biological and epidemiological research; data on risk networks and population-level data to parameterize epidemiological models and simulations specific to rural areas; a subject pool for potential intervention trials related to drug use or its associated harms; and translation opportunities for animal-based research, for which questions of human parallels can be explored for applicability and relevance. In addition to meeting the research needs of RDAR?s Project Leaders and Center members, LNC?s fee-for-service model will allow it to serve the broader research community pursuing work on drug use and addiction and, in the longer term, recruitment and retention of problem-specific longitudinal cohorts for a broad array of behavioral, clinical, and basic research projects.