"1) This paper provides a conceptual framework for counting and categorising peacebuilding activities as well as a hard working-definition of the actions that count as peacebuilding. One of the primary inhibiting factors for assessing peacebuilding cost-effectiveness has been the lack of commonly ag ... reed definitions and confusion about what activities constitute peacebuilding. Without this, it is simply not possible to measure and compare the cost-effectiveness of peacebuilding activities. 2) A comprehensive accounting of global peacebuilding expenditures from 2002 to 2013, using the working definition that was developed in partnership with the UN Peacebuilding Support Office (PBSO) and Peacebuilding Support Group. This is the first known attempt at comprehensively accounting for peacebuilding activities — without this data it is not possible to empirically assess different peacebuilding strategies and assess the cost-effectiveness of them or individual peacebuilding actions. This data shows that peacebuilding activities are unevenly distributed geographically and thematically and are prioritised to differing extents by international donors. 3) A detailed case study of peacebuilding expenditures is presented to analyse an example of peacebuilding success — Rwanda from the wake of genocide to 2014. This analysis shows US$18.35 billion was committed to peacebuilding expenditures in Rwanda from 1995 to 2014. That means peacebuilding commitments in Rwanda from the international community were at least $27 per capita each year for the past 15 years. This demonstrates that the assistance associated with peacebuilding is not exhausted in the five or even ten years following a conflict, meaning that the success of peacebuilding cannot be judged on whether there has been a relapse into a conflict after such a short period of time has elapsed. If some moderate level of peacebuilding expenditure indeed leads to a reduction in violence, and if Rwanda is illustrative of the levels of peacebuilding required to reduce violent conflict, then the current levels of global peacebuilding expenditure are insufficient to build global peace. 4) A global model of the cost-effectiveness of peacebuilding, based on the case study findings and the data generated from them. Using 20 years of peacebuilding expenditure, Rwanda’s experience as a baseline, and combining this with IEP’s research on the global cost of conflict, the paper presents scenario analysis and a model of peacebuilding cost-effectiveness. It finds that using conservative assumptions, the cost-effectiveness ratio of peacebuilding is 1:16, showing that increased funding for peacebuilding would be hugely beneficial not only to peacebuilding outcomes but in terms of the potential economic returns to the global economy. This means that if countries currently in conflict increased or received levels of peacebuilding funding to appropriate levels estimated by this model, then for every dollar invested now, the cost of conflict would be reduced by $16 over the long run. Projected forward ten years from 2016 this would save US$2.94 trillion in direct and indirect losses from conflict. However, achieving this outcome would require an approximate doubling of peacebuilding toward the 31 most fragile and conflict affected nations of the world. Of course, this does not preclude other important factors for peacebuilding success such as the external influence of other states or the role of political elites, but rather establishes a working framework for resources required for programmatic peacebuilding activities. 5) In order to take this research forward, this paper also provides detailed approaches for a future research agenda to look deeper into the ultimate aim of assessing the cost-effectiveness of particular peacebuilding interventions. Through drawing upon existing impact evaluations on peacebuilding interventions in Liberia, it demonstrates a basic approach to how the cost-effectiveness of specific peacebuilding interventions could be compared within a specific context. However, this approach demonstrates the long-term needs for a fully-fledged research agenda in this area. Impact evaluations are resource intensive and require a very significant upscaling of research. Currently, it is estimated that there are only 61 impact evaluations globally on programmes with peacebuilding outcomes. In other domains such as health or education there are hundreds and thousands of such impact evaluations, which highlights the clear need for more impact evaluations in peacebuilding." (Executive summary) more