Results Based Financing (RBF) is an approach that is increasingly being utilized in various countries across different settings and levels to facilitate improvements to health system functionality and priority health outcomes. Since 2008, the Health Results Innovation Trust Fund (HRITF) has invested US $420 million in HRITF linked to US $2.4 billion in financing from the International Development Association to implement RBF programs in 32 countries. In many of these low- and middle-income nations, the Bank’s board has also approved additional financing to expand these programs following the initial success of these programs. As well as sustaining these initiatives, the HRITF’s learning portfolio evaluates the design, implementation, and impacts of the pilot programs funded by HRITF. Both quantitative and qualitative evaluations are utilized to assess, learn, and understand the impact of these programs.