Pay for success (PFS) financing harnesses philanthropic or other private capital to fund evidence-based programs, with government repaying investors only if the programs achieve specified outcomes. As of 2016, there have been 11 PFS deals in the United States targeting a range of social outcomes, from early childhood education to chronic homelessness to recidivism. PFS has the potential to expand evidence-based policymaking by incentivizing the use of research when selecting programs and expanding our knowledge of what works and what doesn’t through rigorous evaluation.