The One-Degree Daily (1DD) technique provides globally complete daily precipitation estimates on a 1°×1° lat/long grid using multisatellite observations. For latitudes between 40°N and 40°S, the Threshold-Matched Precipitation Index (TMPI) uses 3-hourly infrared brightness temperatures (Tb) to estimate precipitation, with thresholds and rain rates adjusted monthly based on satellite data. At higher latitudes, precipitation is estimated using rescaled data from the Television and Infrared Observation Satellite Operational Vertical Sounder (TOVS). The TMPI and TOVS data are combined to ensure consistency with the Global Precipitation Climatology Project (GPCP) satellite-gauge (SG) estimates. The GPCP has approved the 1DD as an official product, with data available from 1997 to 1999. The 1DD dataset shows good continuity in time and across data boundaries, and validation shows high mean absolute error for individual gridbox values, but improves with time/space averaging. The TMPI uses probability matching concepts to adjust Tb and rain rate thresholds, and an audit procedure is used to correct outliers. The 1DD dataset is particularly useful for regional/temporal averages and has been validated against the Oklahoma Mesonet and Baltic Experiment data, showing reasonable performance. The 1DD is also used to analyze precipitation events, such as Hurricane Mitch, and to study the Indian monsoon. The 1DD is a first-generation technique for estimating global daily precipitation and has been accepted as an official GPCP product. Future developments include error estimates, individual 3-hourly estimates, and improved algorithms for accuracy.The One-Degree Daily (1DD) technique provides globally complete daily precipitation estimates on a 1°×1° lat/long grid using multisatellite observations. For latitudes between 40°N and 40°S, the Threshold-Matched Precipitation Index (TMPI) uses 3-hourly infrared brightness temperatures (Tb) to estimate precipitation, with thresholds and rain rates adjusted monthly based on satellite data. At higher latitudes, precipitation is estimated using rescaled data from the Television and Infrared Observation Satellite Operational Vertical Sounder (TOVS). The TMPI and TOVS data are combined to ensure consistency with the Global Precipitation Climatology Project (GPCP) satellite-gauge (SG) estimates. The GPCP has approved the 1DD as an official product, with data available from 1997 to 1999. The 1DD dataset shows good continuity in time and across data boundaries, and validation shows high mean absolute error for individual gridbox values, but improves with time/space averaging. The TMPI uses probability matching concepts to adjust Tb and rain rate thresholds, and an audit procedure is used to correct outliers. The 1DD dataset is particularly useful for regional/temporal averages and has been validated against the Oklahoma Mesonet and Baltic Experiment data, showing reasonable performance. The 1DD is also used to analyze precipitation events, such as Hurricane Mitch, and to study the Indian monsoon. The 1DD is a first-generation technique for estimating global daily precipitation and has been accepted as an official GPCP product. Future developments include error estimates, individual 3-hourly estimates, and improved algorithms for accuracy.