The Global Energy and Water Cycle Experiment (GEWEX) Continental-Scale International Project (GCIP) was focused on the Mississippi River basin to take advantage of the existing meteorological and hydrological networks that were upgraded with new Doppler radars, wind profilers, and automatic weather stations together with an upgraded version of the Geostationary Operational Environmental Satellites (GOES) operated by the United States. The Mississippi River basin encompasses a wide range of climate, soil moisture conditions, vegetation types, and surface topography. The GCIP Science Plan identified the major phase of GCIP as the 5-year Enhanced Observing Period (EOP), targeted for 1995 to 2000, during which original data sets would be assembled for the GCIP database. GCIP organized these data into in situ, model output and satellite remote sensing data. Data from three mesoscale models were included with the start dates ranging from May 1995 to April 1997. A number of GCIP Initial Data Sets (GIDS) were prepared, starting in 1993, to provide the data services support during the buildup period before the 5-year EOP. The data sets were compiled for on-line access by GCIP investigators and were also published on CD-ROM. A number of special data sets, in addition to the EOP data sets, were compiled during the course of GCIP. Some of the most significant special data sets are summarized in this paper.