The Orbiting Carbon Observatory (OCO) is currently scheduled for launch in December 2008. This NASA Earth System Science Pathfinder (ESSP) mission will make spatially resolved measurements of CO2 over the sunlit hemisphere the Earth. These measurements will be analyzed with chemical tracer transport models to retrieve CO2 sources and sinks on regional scales and quantify their variability over the seasonal cycle. This seminar will describe the mission objectives, approach, and anticipated products.