NASA's future science missions to investigate the structure and evolution of the universe require highly efficient, very low temperature coolers for low noise detector systems. We propose to develop a highly efficient, lightweight Active Magnetic Regenerative Refrigeration (AMRR) system that can continuously provide remote/distributed cooling at temperatures in the range of 2 K with a heat sink at about 15 K. The AMRR system uses a vibration-free, reversible cryogenic circulator and innovative Micromachined Active Magnetic Regenerators (MAMRs) to achieve a large cooling capacity and very high thermal efficiency. The MAMRs use an innovative flow channel configuration and novel micromachining technologies to achieve very high thermal and flow performance. In Phase I we will prove the feasibility of our approach by demonstrating critical fabrication methods for the micromachined regenerator and its thermal and flow performance through detailed analysis. In Phase II we will build and demonstrate a full-scale micromachined regenerator for a prototype AMRR system that can provide 50 mW of cooling near 2 K. In Phase III we will demonstrate a complete AMRR system incorporating the MAMRs and Creare's innovative reversible cryogenic circulator.