The tri-agency Integrated Program Office (IPO) manages the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the Defense Meteorological Satellite Program (DMSP) and Polar-orbiting Operational Environmental Satellites (POES) that have provided global data for weather forecasting and environmental monitoring for over 40 years. Beginning in late 2009, NPOESS spacecraft will be launched into three orbital planes to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. NPOESS will observe more phenomena simultaneously from space than its operational predecessors and deliver a data volume significantly greater than the POES and DMSP systems with substantially improved delivery of data to users. Higher (spatial, temporal, and spectral) resolution and more accurate imaging and sounding data will enable improvements in short- to medium-range weather forecasts. NPOESS will support the operational needs of meteorological, oceanographic, environmental, climatic, and space environmental remote-sensing programs and provide continuity of data for climate researchers. With the development of NPOESS, we are evolving operational "weather" satellites into integrated global environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system-atmosphere, ocean, land, and the space environment.