The International Space Station (ISS) Node 1 element plays a unique role in the overall environmental control and life support system architecture for the total station. This system must function with other modules as they are attached on orbit, survive the long on-orbit loiter period with exposure to extreme cold, and provide services to the crew upon arrival. The testing and checkout program for this system consists of a series of tests and analyses used for buildup and verification. Both testing and analysis are used for final verification for system buildup test and total functional test. The purpose of this paper is to review the test and checkout program for the Node 1 element and to review how it meets on-orbit requirements. Lessons learned and recommendations for future space station modules are included.