Book excerpt: Expectations are high regarding the potential benefits of public-private partnerships (PPPs) for infrastructure development in low-income countries. The development community, led by the G20, the United Nations, and others, expects these partnerships between goverments and private companies in infrastructure service provision to aid "transformational" mega-projects, as well as efforts to achieve the Sustainable Development Goals. Yet PPPs have been widely used only since the 1990s, and discussion of their efficacy is still dominated by best-practice guidance, academic studies that focus on developed countries, or ideological criticism. Meanwhile, practitioners have quietly accumulated a large body of empirical evidence on the actual performance of PPPs. The purpose of this book is to summarize and consolidate what this critical mass of evidence-based research indicates about PPPs in low-income countries, and thereby develop a more realistic perspective on the practical value of these mechanisms. With a primary focus on Sub-Saharan Africa, though drawing on critical insights from other regions, it demonstrates that the benefits of such partnerships will only be realised if expectations remain modest and projects are subject to transparent evaluation and competition.