This project facilitates structure determination from electron microscopy. Suitable software, hardware, and scientific expertise has been provided to allow other scientists, primarily at NIH, to use image processing and computer reconstruction to determine or understand a specimen's structure. Types of data analyzed include intermediate filaments, clathrin triskelion legs, and membrane structures. The micrographs were taken with a Philips EM400T microscope and the Brookhaven STEM. some micrographs were preselected by optical diffraction. Negatives were digitized on a Perkin-Elmer 1010MG microdensitometer and analyzed by means of the PIC computer system. Results were photowritten on the Perkin-Elmer microdensitometer or on a Matrix camera station. Images were processed using software developed primarily at NIH. Software development will continue as needed. We anticipate addition of some 3-D image processing capabilities. In addition, as new biological structures become available for analysis, these will be examined.