The assembly of the International Space Station is a major aerospace engineering endeavor currently being conducted in low-Earth orbit by a consortium of governmental and inter-governmental space agencies. When assembly is complete the International Space Station (ISS) will be have a pressurized volume of approximately 1,000 cubic meters.

Zarya, the first ISS module, was launched by a Proton rocket in November 1998. The STS-88 shuttle mission followed two weeks after Zarya was launched, bringing Unity, the first of three node modules, and connecting it to Zarya. This bare 2-module core of the ISS remained unmanned for the next one and a half years, until in July 2000 the Russian module Zvezda was added, allowing a minimum crew of two astronauts or cosmonauts to be on the ISS permanently.

When assembly is complete, the ISS will have a pressurized volume of approximately 1,000 cubic meters, a mass of approximately 400,000 kilograms, approximately 100 kilowatts of power output, a truss 108.4 meters long, modules 74 meters long, and a crew of six. Building the complete station will require more than 40 assembly flights. Of these flights, currently 33 are planned to be Space Shuttle flights, with 21 ISS-shuttle flights currently flown and 13 more planned between 2007 and 2010. Other assembly flights consist of modules lifted by the Russian Proton rocket or in the case of the Pirs Airlock by a Soyuz rocket.