Input subsidies currently are one of the more contentious agricultural policies in sub-Saharan Africa. On the one hand, they can play a critical role in providing inputs to poor farmers. On the other hand, they typically raise questions about appropriate targeting, implications for agricultural budgets, and potential misuse for personal or political gain. The resurgence in agricultural input subsidies that began in the early 2000s and expanded throughout Africa during that decade precipitated a new wave of rigorous empirical research on the effectiveness of different modalities and pointed to some clear challenges across countries for these interventions (see Jayne and Rashid 2013; Minot and Benson 2009). Nevertheless, reforms to improve the effectiveness of agricultural input subsidy programs (ISPs) has occurred at a variable pace across countries and resulted in different design and implementation modalities. Understanding the reasons for such policy variation is useful for the international development and research communities in order to recognize when evidence is likely to have an impact on policymakers, which stakeholder interests are most important to consider, and how to disentangle whether it is low capacity, insufficient political will, or both that ultimately stymies input subsidy reform.