Scaled Composites Model 316 SpaceShipOne completed the first privately-funded human spaceflight on June 21, 2004.

SpaceShipOne was an experimental air-launched suborbital spaceplane that used a hybrid rocket motor. The design featured a unique "shuttlecock" reentry system where the rear half of the wing and the twin tail booms folded upward along a hinge running the length of the wing; this increased drag while remaining stable. The achievements of SpaceShipOne are more comparable to the X-15 than orbiting spacecraft like the Space Shuttle. Accelerating a spacecraft to orbital speed requires more than 30 times as much energy as lifting it to 100 km.

SpaceShipOne was developed by Scaled Composites, Burt Rutan's aviation company, in their Tier One program, without government funding. On June 21, 2004, it made the first privately-funded human spaceflight, and on October 4, it won the $10-million Ansari X Prize, by reaching 100 kilometers in altitude twice in a two-week period with the equivalent of three people on board, with no more than ten percent of the non-fuel weight of the spacecraft replaced between flights. Development costs were estimated to be $25-million, funded completely by Paul Allen.

New funding comes from British tycoon Richard Branson, who is to fund the successor SpaceShipTwo for his new company Virgin Galactic through a $21 million US deal. During its testing regime, SpaceShipOne set a number of important "firsts", including first privately-funded aircraft to exceed Mach 2 and Mach 3, first privately-funded spacecraft to exceed 100km altitude and first privately-funded reusable spacecraft.

SpaceShipOne is registered with the FAA as . 'N' is the prefix for US-registered aircraft; '328KF' was chosen by Scaled Composites to stand for 328 (k{ilo}) feet (about 100 kilometers, the officially designated edge of space). The original choice of registry number, N100KM, was already taken. N328KF is registered as a glider, reflecting the fact that most of its independent flight is unpowered.

All of its flights were from the Mojave Airport Civilian Flight Test Center.

SpaceShipOne's first flight, 01C, was an unmanned captive carry flight test on May 20 2003. Glide tests followed, starting with flight 03G on August 7, 2003. Its first powered flight, flight 11P, was made on December 17, 2003, the 100th anniversary of the first powered flight.

On April 1, 2004, Scaled Composites received the first license for sub-orbital rocket flights to be issued by the US Department of Transportation. This license permitted the company to conduct powered test flights over the course of one year. On June 17, 2004, Mojave Airport reclassified itself (part-time) as the Mojave Spaceport.

Flight 15P on June 21, 2004, was SpaceShipOne's first spaceflight, and the first privately funded human spaceflight. Ansari X Prize flights followed, with flight 17P on October 4, 2004, winning the prize.