This second version of the PPP Reference Guide, as the first one, presents a global overview of the diversity of approaches and experiences in the implementation of PPPs, providing an entry point to the substantial body of knowledge on PPPs that has been built up by practitioners in governments, the privatesector, international institutions, and academics. With due care not to increase the overall size of the Guide, this version includes new references and examples. The PPP Reference Guide seeks to provide advice on what PPP practitioners should know, rather than provide advice on what to do. The Guide sets out the main topics, looks at the key issues that must be addressed, and provides what we consider the most important references that PPP practitioners can turn to for answers and to enhance their own knowledge and understanding. It is structured into separate sections that focus on three main areas, firstly what are PPPs, when might they be used and the advantages and disadvantages relative to public provision; secondly the policy, legal and institutional frameworks that should be put into place to help improve their effectiveness; and finally the ways in which PPP projects can be developed and implemented. A diverse range of case studies and institutional solutions, from all parts of the world, are presented in the PPP Reference Guide.