In this paper, conceptual aspects of Public-Private Partnerships (PPP) in infrastructure are examined, in their economic, financial and project management areas. Based on the above, a structural equations model is built, which allows estimating an Index to be applied in the early stages of the design of APP schemes, in such a way as to help complement the decision-making process about the convenience of using this modality of execution and management of infrastructure projects and public services. The Index is constructed with information extracted from a questionnaire applied in Colombia, Chile, Mexico and Peru, and as such, it can at least be generalized to the rest of the Latin American countries.