ABSTRACT Administrative Core The mission of the Multicenter Osteoarthritis (MOST) study is to conduct, facilitate, and promote high impact research on the etiology and prevention of osteoarthritis (OA) and its consequences of pain and loss of function. During the proposed 4th cycle of MOST (MOST4), we plan to accomplish this goal through the acquisition, management, analysis and sharing of data on OA, risk factors and functional consequences of disease. The primary goal of the MOST4 Administrative Core is to ensure that processes are in place and functioning to support the accomplishment of this mission. The Administrative Core will manage finances, and the following interactions: 1) internally among the study units (the Cores (Clinical Data Collection and Management, Analysis, Imaging) and Projects); 2) with external researchers; 3) between institutions involved in the MOST study including Boston University; University of Alabama, Birmingham; University of California, San Francisco; University of Iowa; the funding agency (NIA); reading centers; and specialized laboratories.The Administrative Core will be under the leadership of Core co-Leaders Drs. David Felson and Tuhina Neogi, supported by an Executive Committee consisting of the other Cores' leaders. The overall team of MOST4 investigators include a mix of senior experienced NIH-funded faculty and junior faculty establishing their careers with a focus on studies of OA, pain and disability. The first cycle of the MOST study (MOST1) was funded in 2001, and investigators affiliated with this cohort have a long history of collaboration, having published over 180 papers reporting important findings related to OA epidemiology and risk factors, pain, function, and other outcomes. Among the unique features of the study has been the multidisciplinarity of its investigators and research. A range of topics have been studied, including MRI findings in the knee, pain sensitization, biomechanical data such as the ground reaction force, measurement of muscle function, studies of crystal deposition, assessment of physical activity, among others. The current proposal for the 4th cycle of MOST (MOST4) represents an expansion of this multidisciplinary focus. The goals of the Administrative Core are to provide leadership to successfully manage the overall study's execution; plan, direct and integrate all MOST study activities; provide transparent communication across projects and cores; and foster cross-project collaboration. We will accomplish these goals through providing leadership and administrative oversight for the following Specific Aims: Scientific & Operational Management, including single Institutional Review Board processes; Financial Management; Study Output Management & Dissemination; Pilot Grant Program; Community Advisory Board Engagement; Communications & External Collaboration. Through these activities, the Administrative Core will ensure the successful operations of MOST4 under the strong and c...