Despite broad consensus among many in the scientific research, data, and policy communities about the importance of preserving and sharing research data, there are significant concerns about the adequacy of measures being taken today to enable these activities. The difference between current activities and best or ideal policies and practices constitutes a gap that this article describes: the stewardship gap—a gap that will require innovative strategies by researchers, research organizations, and research sponsors to address. The authors interviewed 46 active researchers, drawn from a variety of scientific domains, to understand their perspectives on the value of their research data, the length of time their data would remain valuable, and the kind and extent of commitments in place to ensure ongoing preservation of valuable data. In all, the researchers provided descriptions, valuations, and prospective plans for 120 datasets produced in 46 projects. Four concepts are valuable for understanding our findings: the kinds of commitment researchers receive from data stewards; who takes responsibility for stewardship; the value of the data as perceived by the researcher and others; and the length of time over which data are valuable and commitments exist. Based on this study as a representation of the larger cohort of data created with federal and foundation R&D support, research data are "at risk." This is especially so when data are valuable and the length of time for which there is a preservation commitment is less than the length of time that the data will have value. Closing gaps in commitment and responsibility is essential if valuable data are to be effectively preserved. This calls for clear policy directives from government agencies and other research sponsors in partnership with research-performing institutions, designation and acceptance of responsibility, and supporting human and financial investments for the research data the community deems as valuable.Alfred P. Sloan Foundation; Rensselaer Polytechnic Institute; University of Colorado Boulderhttps://deepblue.lib.umich.edu/bitstream/2027.42/146759/6/Stewardship Gap Article for deep blue-updated January 2019.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146759/1/Stewardship Gap Article for Deep Blue.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146759/2/Stewardship Gap Supplemental Materials for Deep Blue.pdf1517137Description of Stewardship Gap Article for deep blue-updated January 2019.pdf : Main Article (January 2019)Description of Stewardship Gap Article for Deep Blue.pdf : Previous VersionDescription of Stewardship Gap Supplemental Materials for Deep Blue.pdf : Supplemental Material