"I can foretell the way of celestial bodies, but can say nothing of the movement of a small drop of water" - Galileo Galilei. Water related issues facing Galileo still challenge the hydrologic community today. Freshwater research conducted by the National Oceanic and Atmospheric Administration (NOAA) is focused on: (1) water cycle monitoring and prediction; (2) atmosphere and land model prediction; (3) using the full information content of weather and climate forecasts in hydrologic applications; (4) improving hydrologic modeling; and, (5) enhancing hydrologic data assimilation techniques. The National Weather Service (NWS) Office of Hydrologic Development (OHD) is actively addressing a number of issues critical to "the movement of a small drop of water" as it passes from the atmosphere to the oceans. OHD scientists are providing quantitative precipitation estimates by merging information from radar, satellite, and rain gauges. OHD is sponsoring a Distributed Model Intercomparison Project, which will guide NWS distributed model development and implementation. OHD is developing a new generation of process-based snow and distributed hydrologic models in collaboration with other NOAA components and the academic community. In addition, OHD researchers are adapting advanced models of the complex flow in large rivers and providing a GIS-based mapping capability to display river forecast inundation maps. Advances in NWS hydrologic service delivery depend on probabilistic hydrologic modeling to produce ensemble stream flow forecasts. These scientific enhancements are validated through a hydrologic forecast verification program. Hence, NWS freshwater research is helping to couple other core NOAA components and complete the hydrologic cycle.