This project involves the upgrade of the Redshift and Early Universe Spectrometer from a 1x32 engineering-grade thermistor array into a 3x50/5x50/3x25 (spatial x spectral) Transition Edge Sensor science-grade array. The work is a follow-on to work being conducted under NSF award #0705256. The array will be deployed on the James Clerk Maxwell telescope and the Caltech Submillimeter Observatory, and would eventually be deployed on the Atacama Pathfinder Experiment telescope in Chile in 2008. The project will involve several undergraduate and graduate students, and involves collaborations with other institutions and with industry and national research centers.