The Electron Microprobe (EMP), also known as Electron Probe X-ray Microanalyzer (EMPA or XMA) is a powerful and well established analytical tool that provides quantitative analysis of element abundances in a variety of earth, extraterrestrial and artificial materials including minerals, glasses, ceramics, metals and superconductors. It provides non-destructive, in situ analysis of a flat surface with a spatial resolution of ~2 micron. It also provides excellent high resolution scanning electron imaging capabilities. It allows an easy transition between backscattered electron scanning (or image) mode where one can see compositional variations in the sample to a spot (or analysis) mode where a one micron diameter area of choice can be chemically analyzed. The instrument, coupled with high speed and large memory computers, also has large area (up to 80 mm x 80 mm) mapping capability of compositional variations in multi-phase materials. The EAPS electron microprobe facility consists of two JEOL JXA-733 Superprobes. One is equipped with five wavelength dispersive spectrometers. Two of these spectrometers contain Ovonics synthetic multilayered diffracters, that are optimized for light element analysis (F, O, N, C and B). The second microprobe is equipped with four wavelength dispersive spectrometers, one of which contain an Ovonics synthetic multilayered diffracter. Both instruments have computer-automated spectrometers and stages, NORAN energy dispersive spectrometers, and electron beam automation. Software for automated quantitative chemical analysis, image analysis and particle sizing provides the capability of characterizing the spatial distribution of chemical composition on a surface, and combining chemical information with shape and size. Both the quantitative analysis and the imaging softwares are PC-based running under Windows 95/NT. The analysis output data can be easily loaded in popular spreadsheets such as Excel. The images are stored in TIFF format permitting them to be opened by a large range of image analysis software products. The energy dispersive spectrometer electronics and associated software also reside in the PC, which enables easy maintenance and troubleshooting. The microprobes are in separate rooms with appropriate air conditioning, ventilation and electrical power needs. A third room houses sample preparation facilities: carbon coater, polishing wheels and grinding equipment.