The thermal design and analysis of the Earth Observing-1 (EO-1) spacecraft, built by Swales Aerospace for NASA's Goddard Space Flight Center (GSFC), consisted of a Thermal Synthesis System1 (TSS) geometric math model (GMM) and a SINDA/FLUINT2 thermal math model (TMM). These models took advantage of the submodel capability of TSS and SINDA/FLUINT providing a simplified approach for merging spacecraft and instrument models. In addition to the spacecraft thermal model, there is the Advanced Land Imager (ALI) instrument model by MIT/LL, the Hyperion instrument by TRW, the Atmospheric Corrector (AC) instrument by GSFC, and the New Millenium Program (NMP) experiments. Separate thermal models were developed for each NMP experiment which included, the Pulse Plasma Thruster (PPT) by Primex, Lightweight Flexible Solar Array (LFSA) by Lockheed, X-Band Phased Array by Boeing and the Carbon-Carbon Radiator that was developed as a joint effort between NASA and industry. EO-1 will fly in a sun-synchronous, 705 km circular orbit, one minute behind the Landsat-7 Spacecraft. Using data from Landsat researchers can validate the ALI, Hyperion, AC and NMP technologies performance over EO-1's one-year primary mission duration.The EO-1 spacecraft thermal design is a cold bias design using passive radiators, regulated conductive paths, thermal coatings, louvers, thermostatically controlled heaters and multi-layer insulating (MLI) blankets. Swales Aerospace was responsible for providing sufficient cooling paths for the spacecraft electronics and instrument interfaces. In addition, only survival heater power was allocated for the spacecraft, therefore, it was imperative that the thermal radiators be designed to maintain components for all phases of the mission without the aide of operational heaters.Swales Aerospace is responsible for the integration of the instrument and experiment thermal models with the EO-1 spacecraft thermal model. The instrument and experiment models were delivered to Swales in a variety of formats and engineering units adding to the complexity of model integration. Fortunately, the TSS and SINDA/FLUINT submodel feature could provide some relief and help simplify the process. In today's industry where better, faster, cheaper seems to be the philosophy, it is imperative to have thermal analysis tools that are quick and accurate.This paper describes the design philosophy, thermal control objectives, thermal design results, thermal model analysis and lessons learned from analysis and test results of the EO-1 satellite.