There is a defined need for long term earth based testing for the development and deployment of two-phase flow systems in reduced-gravity, including lunar gravity, conditions. The proposed study intends to develop a scaling methodology to meet this requirement. A hierarchical two-tiered scaling approach will be used to obtain scaling relations for an entire system (integral scale), individual components of the system and local phenomena. The final product of the Phase I effort will be a rigorous scaling methodology along with important non-dimensional numbers which can be used for developing earth-based systems to study reduced-gravity two-phase systems and/or phenomena. The feasibility of the approach will be demonstrated in Phase I by using data available in literature that has been acquired in reduced-gravity as well as earth based conditions. As part of Phase II a scaled experimental facility will be designed and confirmatory experiments performed.