AbstractAmong various project delivery methods, there is a growing tendency to deliver transportation infrastructure projects, particularly highway projects, through public–private partnerships (PPPs). This necessitates further investigations on PPP arrangements. Despite previous research efforts, a question remains unanswered: What are the contributing criteria for selecting projects that fit the PPP method, and of these, which factors play key roles? This study aims to address such a question through a Delphi study approach. To meet this objective, experts at state DOTs participated in interviews and questionnaire surveys during two rounds of a Delphi study. After achieving a consensus among responses, this study identified factors: the PPP project’s screening factors and characteristics, requirements for an evaluation panel to assess a potential project, common risks, risks needed to provide appropriate incentives to private parties, requirements for involved staff, specializations required in PPP units to facilitate project phases, roles of the public sector or federal government or state, associated factors to enabling legislation, economic analysis, and suitable project size. Some of the major findings are that PPPs are suitable for large projects, the value of money should be a mandatory study, an economic analysis must be performed by comparing different delivery methods, and it should be determined whether PPPs are legal (and allowed) in the state. The primary contribution of this research to the body of knowledge is to focus academicians’ and industry professionals’ attention on PPP highway project selection criteria and the factors that are required to maximize project performance and benefits.