It is proposed to establish an electron microscopy facility at Brookhaven which will provide for the efficient use of expensive instrumentation essential for progress in biological structure studies. The laboratories will be used jointly by Brookhaven staff and academic biologists. The initial goal will be the introduction into research use of a scanning transmission electron microscope of the design introduced by Dr. A. V. Crewe. An improved model of the 100 KeV design (2.0 A resolution) is approaching completion in the Biology Department of Brookhaven National Laboratory and will be ready for use towards the end of 1975. A committee composed of Brookhaven biologists and academic biologists will apply the new microscope to the study of a variety of biological materials on a time-sharing basis. The application includes research proposals of considerable scope which are expected to expedite the evaluation of the microscope for biomedical research. The facility will also provide for transmission microscopy, and for experimental work in sample preparation, image analysis and data treatment and will offer the possibility of new instrumental developments for electron microscopy. Among these are systems for data acquisition and analysis, new detectors for data acquisition and analysis, new detectors for obtaining additional information, and specialized specimen stages. Access to the facility will be open to all qualified biomedical scientists and will be regulated by a committee to promote its efficient function as a national facility in health-related research and training.