The Hubble Space Telescope was designed to be periodically serviced on-orbit during its 15 year mission. Servicing carriers have been designed for these servicing missions and were previously flown during the Hubble Space Telescope Servicing Mission 1, Space Transportation System 61, December 1993. In preparation for the Hubble Space Telescope Servicing Mission 2, the Hubble Space Telescope contamination control philosophy was reviewed to determine its applicability to reflown hardware. The contamination control program currently in place for the Hubble Space Telescope Servicing Mission 2, evolved from the Hubble Space Telescope Servicing Mission 1 contamination control program. The challenge of the Hubble Space Telescope Servicing Mission 2 contamination control program was to maintain the integrity and outgassing certification of the reflown hardware while accommodating configuration changes to the hardware. Environmental control of the hardware, materials screening and outgassing certification of added hardware were the important features of the program.