The World Humanitarian Summit of 2016 agreed a new agenda for “localization of aid", committing to a “Grand Bargain” to increase international investment in the leadership, capacity and delivery of local humanitarian organizations. Investment in long-term institutional capacity of local actors, including civil society, is a critical piece of this – based on a shared understanding among those with long experience in the humanitarian community that it will lead to more effective and less costly aid. However, change of this kind requires changing minds well beyond the confines of those who have, with their own eyes, seen the impact of such initiatives. Evidence is still needed of the long-term benefits (as well as the challenges) of such efforts. This Study is a contribution to these sector-wide learning objectives from IFRC and 5 of its member National Red Cross and Red Crescent Societies of Indonesia, Kenya, Lebanon, Mexico, and Turkey. It demonstrates that long-term purposeful investment in “National Society Development” (NSD) (including “organizational development” (OD) and “capacity strengthening” (CS) increased humanitarian impact in challenging, diverse and complex environments. The five case studies contained in part 2 of this report document the ways in which sustained longitudinal NSD work and investments over a period of 10 years or more have resulted in a profound transformation of those five National Red Cross and Red Crescent Societies (NS), that in turn has increased and improved humanitarian impact. Each NS achieved a significant transformation process over 10 years through a combination of locally-led visionary leadership, strategic longitudinal NSD initiatives and partnerships, and a balanced combination of OD and CS work. Each story demonstrates the multiple accelerators to strengthened humanitarian outcomes and impact in communities.