The International Space Station (ISS) Environmental Control and Life Support (ECLS) system includes regenerative and non-regenerative technologies which provide the basic life support functions to support the crew, while maintaining a safe and habitable shirt-sleeve environment. Significant progress has been made over the past year in preparing for the initial assembly phase of the ISS program, now scheduled to begin construction in November 1998. Almost all ECLS hardware supporting the Phase 2 ISS assembly period has been delivered, with significant element integration testing completed for the early elements. Additionally, design activities have begun on the U.S. Phase 3 regenerative ECLS hardware. This paper provides a summary of the U.S. Environmental Control and Life Support (ECLS) system activities over the past year.