The Space Station Freedom (SSF) Environmental Control and Life Support System (ECLSS) Atmosphere Revitalization (AR) subsystem conditions the cabin atmosphere to provide a safe habitable environment for the 4-person astronaut crew. The first phase of the ECLSS development testing, namely the AR POST, focuses on the SSF Man Tended Capability (MTC) configuration. The scheduled 34-day integrated AR POST was conducted by Boeing at Marshall Space Flight Center (MSFC) Building 4755, Huntsville, Alabama and completed March 21, 1992. A test timeline is presented in Figure 1. This test was the first time the three baselined ECLSS Man Tended Capability (MTC) AR assemblies were integrated and operated in a closed door chamber in which the internal atmosphere was monitored. This paper details the initial results of the Integrated AR POST. Future considerations for the Integrated Single String POST are also discussed.The next phase of the POST program involves Integrating the Water Recovery and Waste Management (WRM/WM) subsystem with the AR subsystem to attain full single string ECLSS Integration. The two ECLSS development tests that follow the POST program are the Baseline Operational system Test (BOST) and the Manned Operational System Test (MOST). The BOST will be the first time flight qualifiable hardware is used. The MOST will involve a 90-day continuous test with a participating crew of four persons using the BOST facility. This test activity is being conducted by the Boeing Defense and Space Group under contract NAS8-50000 to the Marshall Space Flight Center.