NASA's future spacecraft require advanced thermal management technologies to provide effective cooling for multiple instruments and reject heat through multiple radiators. To meet this need, we propose to develop a reconfigurable two-phase pumped loop that can accommodate a complex network of evaporators and multiple radiators. The pumped loop has two performance features: 1) reliable refrigerant circulation with a mechanical pump even when the refrigerant flow exiting the radiators is a two-phase flow with significant vapor quality, and 2) reliable flow distribution among evaporators to minimize flow maldistribution due to heat load variation. These features are achieved by a combination of an innovative loop configuration and Creare's proven enabling components. In Phase I, we will prove the feasibility of reliable refrigerant circulation through building and testing a proof-of-concept pumped loop with key features, optimizing the pumped loop design and predicting its performance. In Phase II, we will build and test an integrated pumped loop with multiple evaporators and heat sinks and demonstrate its performance in a representative thermal environment.