Bioreactor technology is currently being developed by a team of NASA and major aerospace companies to provide capabilities for water reclamation within a Regenerative Life Support System (RLSS). An integrated approach is being used for this development process consisting of fundamental laboratory studies, full-scale experimental studies and mathematical modeling.The laboratory studies are focused on a series of identical bioreactors which are being used to develop an understanding of the kinetics, growth characteristics, and viability of the microbial population in the reactors through variation of key parameters. These studies have provided insight into system control issues, development of advanced reactor design concepts, and establishment of key parameter values for the mathematical modeling effort.The full-scale experimental studies are being used to develop a complete water reclamation system founded on a biologically-based primary water processor. These studies are uncovering the interactions between the biological system and the supporting physical/chemical systems and validating the use of a biological processor for water reclamation.The mathematical models are being developed to help guide the laboratory experimental studies and to assist in the full-scale system design. Two types of models have been developed. The first is a detailed model, based on first principles, which is being used to predict test bed performance and to aid in design of advanced bioreactor concepts. The second is a simplified version of the first model which uses approximations to simplify the mathematics to a level more suitable for use in a systems-level model.This paper describes the integrated approach and presents results from experimentation and modeling efforts conducted in 1994 and 95.