Precipitable Water Vapor (PWV) is defined as the amount of liquid water that would be produced if all of the water vapor in an atmospheric column were condensed. It is a very useful parameter for forecasters to determine atmospheric stability and the probability of convection and severe weather forecast using Numerical Weather Prediction (NWP) models. The total water content of the atmosphere is also a key climate feedback parameter in global climate models (GCMs). The Atmospheric Infrared Sounder (AIRS) on the NASA Aqua satellite is the first of a new generation of satellite sensors that provides the capability to retrieve water vapor profiles at high vertical resolution. The operational follow-on to the AIRS is the Joint Polar Satellite System (JPSS) Cross-track Infrared Sounder (CrIS) planned for launch on the NPP satellite in late 2011. The CrIS will provide the U.S. component of the joint U.S./European operational weather satellite system. The Infrared Atmospheric Sounding Interferometer (IASI) was launched on METOP-A in October 2006 and is currently operated by EUMETSAT. A long record of observations is anticipated from this new network of advanced IR sounders that will provide a wealth of information on the thermodynamic state of the atmosphere. Among other atmospheric observables, the NASA AIRS science team has produced a global dataset of PWV beginning in September 2002 and continuing through the current date (July 2011). The accuracy of this dataset will be assessed using ground truth data at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site located near Lamont, OK. Among other instrumentation, this site contains a GPS receiver, part of a larger regional network of ground-based receivers called SuomiNet. The purpose of this study is to compare the retrievals of PWV from satellite-based infrared sounding instruments (AIRS) to ground-based GPS instruments. After assessing the accuracy of the satellite retrievals using ground-truth, the AIRS and GPS observations will be used to validate both climate model predictions from the IPCC AR4 model inter-comparison as well as a NWP regional reanalysis dataset (NARR). Results are presented that highlight the PWV climatology from the satellite sensor data record and quantify the differences and agreement between the satellite retrievals, GPS observations, and model outputs on monthly averages.