SUMMARY. The objective of this project is to support the imaging and image analysis needs of the COBRE Phase 2 program while continuing to support the broader research community. All four Phase 2 Project Leaders propose to identify and characterize the factors that control host responses to viral, bacterial, and parasitic pathogens using confocal, fluorescence and electron microscopy and quantitative image analysis. The Core is well equipped to meet these needs. Core equipment includes a multiphoton microscope for intravital microscopy, a confocal microscope, two epifluorescence microscope systems, one capable of TIRF microscopy and both equipped for live cell imaging, scanning and transmission electron microscopes, and a workstation with several image analysis tools. The Core proposes four specific aims to ensure that COBRE investigators (Phase 2 and Phase 1 Project Leaders) and the broader research community can meet their research goals. First, the Core director and staff will collaborate with COBRE investigators and other members of the research community by assisting with the development of experimental designs and microscopy approaches, analyzing microscopy images, and interpreting data collected in the Core. Second, Core staff will provide training in equipment use, microscopic imaging services, and educational resources to COBRE investigators and other members of the research community. Third, the Core will provide image analysis software tools and expertise to support quantitative microscopy studies by COBRE investigators and other members of the research community. Finally, the Core will upgrade its equipment by replacing an outdated epifluorescence microscope and seeking funding through the S10 Shared Instrumentation Grant Program to replace the Core Zeiss confocal microscope with a new confocal microscope system. The outcome of these aims will be expansion of Core services, increased Core research capabilities, new research opportunities for users and advancement of the Core?s goals to expand the user base and achieve long-term sustainability.