The Constellation X-ray Observatory consists of four identical spacecraft, each carrying a complement of high sensitivity X-ray instrumentation. At the heart of each is the grazing incidence mirror of the Spectroscopy X-ray Telescope (SXT). This mirror has a diameter of 1.6 m, a focal length of 10 m, mass not exceeding ~650 kg. The required angular resolution is 15 arc seconds and the effective area at 1 keV must exceed 7,500 cm2. Achieving these performance requirements in a cost effective way within the allocated mass is accomplished via a modular design, incorporating lightweight, multiply-nested, segmented Wolter Type I X-ray mirrors. The reflecting elements are composed of thin, thermally formed glass sheets, with epoxy-replicated X-ray reflecting surfaces. Co-alignment of groups of reflectors to the required sub-micron accuracy is assisted by precision silicon microstructures. Optical alignment incorporates the Centroid Detector Assembly (CDA) originally developed for aligning the Chandra mirror. In this talk we present an overview of recent progress in the SXT technology development program. Recent efforts have concentrated on producing an engineering unit that demonstrates all the key fabrication and alignment processes, and meets the angular resolution performance goal. Additionally, we describe the initial steps toward flight mirror production, anticipating a Constellation-X launch early in the next decade.