Plant growth lighting design options are explored for CELSS type systems. Plant lighting systems are reviewed for terrestrial horticulture applications and then extrapolated for use on space vehicles. Several in-space lighting systems are discussed as to their relative merits from both a biological and engineering viewpoint. Two promising candidate CELSS lighting systems are described in detail. One of these is an indirect solar illumination concept using fiber optic technology. Finally, interim results from an orbital lighting cycle plant growth experiment are presented. These experiments provide data on various plants grown under lighting conditions that could result from using solar illumination techniques. The lighting conditions are based on low earth orbit space station's orbital cycles. The primary objective in these experiments is to determine maximum plant food production with minimum electrical power consumption.