This Funding Opportunity Announcement (FOA) encourages applications for support of mature structural biology resources at synchrotron facilities. Mature refers to the techniques made available at the resource beamlines: they must be well-established, requiring no significant novel technology development in order to provide utility to the communities they serve or to maintain them as state-of-the-art beamlines. This funding opportunity is limited to resources whose operations recently have been or currently are being supported by NIGMS funding. The intent is to provide access to X-ray beamlines for structural biology research. It is expected that the facility will be maintained or upgraded to current best practices, make its capability and availability known to the biomedical research community through outreach activities, and provide user training and support