A National Aeronautics and Space Administration (NASA) program has been completed which outlined an advanced missions Environmental Control/Life Support System (ECLSS) technology research and development (R&D) plan. The study defined the ECLSS requirements and ECLSS-related unique mission drivers (i.e., mission duration, crew size, etc.) of a broad range of advanced missions currently being considered by the NASA and recommended by the National Commission on Space. The existing ECLSS technologies were assessed and an evaluation was made to determine the potential application of the existing ECLSS technology to the requirements of the future missions. Technology needs were identified and an advanced missions ECLSS technology R&D plan was outlined.