This Funding Opportunity Announcement (FOA) invites a Research Project Cooperative Agreement application (UC4) from the Program Director/Principal Investigator of the Data Coordinating Center (DCC) that is currently managing this large, complex and effective network. This FOA will support new activities, such as a new Biomarker and Mechanisms Panel, to design and possibly implement mechanistic studies using TrialNet subjects and samples, support new approaches to improve TrialNet recruiting and collaboration in partnership with the Clinical Network Hub, support the design and conduct of new prevention trials (as selected by the TrialNet Steering Committee) to replace ongoing trials, or new trials in newly described at-risk populations, and support the design and conduct of new studies in a silent diabetes population (as selected by the TrialNet Steering Committee). In the final 2 years of the award, this FOA will provide funds to continue the ongoing efforts of TrialNet. The DCC will support a wide range of research projects in varying stages of development, implementation and completion. The DCC will provide for data and sample management, including standardized acquisition, quality control, dissemination, and public accessibility.