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XTE covers the 2-200 keV energy range linking ROSAT and CGRO's OSSE, the range of the highest fluxes from accreting compact objects. the XTE area in this range is the largest to date in order to explore sub-millisecond variations in the fluxes from accreting neutron stars and black hole candidates. The copointed PCA (Proportional Counter Array) and HEXTE (High Energy X-ray Timing Experiment) together have a maximum throughput of 170,000 counts $s^{-1}$. The ASM (All Sky Monitor) will detect new or recurrent transients and XTE can be slewed for large area observations within hours, in many cases well before they reach maximum luminosity. Observations of any steady source or contingent observations of transient targets of opportunity can be proposed. XTE has few constraints on its pointing and is expected to be able to accommodate many requests for coordination with either ground-based or other space instruments. At energies above 10 keV the PCA and HEXTE are the most sensitive instruments to date for the observation of weak sources. Seyfert galaxies and quasars with fluxes of a few tenths of milliCrabs will be measured to 30-100 keV in a few days. The 2-10 keV fluxes of many AGN will be well measured in minutes and series of observations as short as 5 minutes can be proposed to monitor longer term variability of sources beneath the sensitivity limit of the ASM (10-30 milliCrab). The ASM light curves will be public results. The observation program of the PCA and HEXTE for the first 9 months, following a 1 month checkout, is now open for proposals.
