A Principled Approach to Infrastructure Project Preparation Facilities outlines a new model of a sustainable Infrastructure Project Preparation Facility (model IPPF). It may serve as a reference guide, as it also provides a wealth of considerations for the design of an IPPF and a series of best practices to introduce new models of partnerships during project preparation. Each IPPF is designed according to distinctive circumstances, implementation constraints and specific strategic and operational aspects. Once these are tackled, three financial aspects should be addressed: 1) sustainable sources of funds, 2) attracting investors and setting appropriate expectations, 3) providing exit options for investors. The report illustrates the different principles and design options through a series of case studies from Infraco Africa, TIMU Energy Holdings, Africa50 Project Development, and the Brazilian Development Bank (BNDES). The key success factors of the IPPF can be applied to Africa and beyond, albeit with some adaptation.