New information is presented on conceptual designs of bioregenerative life support systems, with subsystems defined, sizes estimated, and configurations developed.1 Components are sized by comparison with design data from Spacelab, the space station, commercial practice, and research on new technologies. Designs were developed on a Microstation CAD system, importing existing models such as space station modules where available. Layouts consider component mass and power as well as connections and access requirements. In addition, current efforts in the NASA CELSS Breadboard Facility (CBF) at Kennedy Space Center are described, which may validate some of these design concepts. Design optimization for the next-generation Breadboard Facility is discussed.