While climate change, population growth, and changing land use present formidable challenges to Peru's water security, Peruvian leaders recognize that Natural Infrastructure (NI) is an indispensable complement to gray infrastructure for the country's water security. The road to scaled NI that effectively and sustainably improves water security and climate resilience is far from assured due to several significant constraints. The NIWS will address these constraints by fostering institutional shifts in favor of NI; improving decisions on NI over time through better capacity, information, and tools; and mobilizing that support to implement model projects and portfolios in priority watersheds. These efforts will set into motion a self-sustaining, growing system of public and private project developers, evaluators, payers, implementers, and financiers that will continue to scale NI for water security and resilience in Peru beyond the five years of the Natural Infrastructure for Water Security Project (NIWS). Forest Trends leads the Invierte Verde Consortium, including local partners (CONDESAN and SPDA) and international experts (EcoDecision and Imperial College London). The Consortium will lead the successful execution of NIWS, building upon its long-term engagement with NI developers and the Government of Peru to develop the technical, regulatory, and institutional framework for systematically scaling NI investments through innovative watershed investment mechanisms such as payment for ecosystem services (MRSE) and regulatory reforms in the sanitation sector.