From August 1 to September 15, 2000 over 250 scientists and technicians from over 40 organizations participated in TexAQS 2000, a major air quality study focussed on Houston, Texas The study was one of the largest, most comprehensive and sophisticated studies of urban air quality that has ever conducted in the US. The overall objective of the study was to provide a better understanding of the emissions, and the basic chemical, physical and meteorological processes that determine ozone and fine particle distributions in eastern Texas, and to provide scientific understanding to policy makers to assist them in devising optimal ozone and PM management strategies. Resources for the program included five aircraft; major chemistry sites at Laporte airport adjacent to the Houston Ship Channel, and on the 62nd floor of Williams Tower on the west side of Houston; EPA funded (U. of Texas GC-ARCH Program) aerosol/chemistry sites located up-in- and downwind wind of the Ship Channel, and; a well developed ozone/aerosol monitoring network supported by TNRCC, the City of Houston, and a consortium of industries in the Houston area. Meteorological resources included five wind profilers, and three rawinsonde launch sites. Conditions were ideal for an air quality study with a major O3 episode occurring during late August, early September. The large array of surface and airborne measurements deployed in the program resulted in an unprecedented characterization in space and time, of the concentrations of O3/aerosol precursors, intermediates, and product species in eastern Texas over a range of conditions.