A differentially-pumped, ultrahigh-vacuum (uhv) system has been developed that is capable of 900 °C bakeout and can attain pressures below10−10Torr in as little as one hour, depending upon the thermal mass of the enclosed apparatus. This paper describes a two-part uhv system and some of the design and materials considerations for mechanical, electrical, and optical couplings through the vacuum walls. Suitable solutions to these and related problems are discussed.