An X-Ray Spectrometer using state-of-the-art detector technology will be launched this year on the Clark spacecraft, one of two missions to be flown as part of the Small Spacecraft Technology Initiative. The primary objective of this mission is to demonstrate new technologies for small spacecraft. In keeping with this philosophy, we use two new types of semiconductor X-ray detectors, both operating near room temperature: avalanche photodiodes and cadmiumzinc-telluride detectors. The main purpose of flying these detectors is to test them in a space environment so that they can be used with confidence on future space missions. Measurements of solar flare and gamma-ray burst X-ray emissions will also be made.