This paper examines the public and private sectors' perception of key factors that influence the implementation of Public-Private Partnership (PPP) in the infrastructure development of Afghanistan -one of the poorest countries in the world where decades of conflict has destroyed much of its infrastructure. The data for this study was drawn through a comprehensive research approach that included a literature review; interviews/discussions with professional experts, experienced practitioners, and decision-makers in Afghanistan; as well as a qualitative survey questionnaire. This study identified thirty-seven critical success factors (CSF) that impact the success of PPP projects in Afghanistan. The most important CSFs were determined to be (1) the need for experienced technical and financial experts in the PPP unit of Afghanistan, (2) promotion of various financing mechanisms by PPP law, (3) establishment of clear financial objectives for PPP projects, and (4) up-front cost/benefit analysis. This study further identified CSFs that significantly hindered the success of PPPs in Afghanistan. These included political and legislative instability, absence of risk management experts and long project approval process, and the on-going political and security uncertainty. The result of an independent t-test showed that, with the exception of three factors, there was no significant difference between the perception of the private and public sectors concerning the importance of the identified CSFs. The factors identified in this study should be given utmost consideration by all the stakeholders to ensure the successful implementation of PPPs in the infrastructure development of Afghanistan. The findings of this study could also be used by researchers in Afghanistan and other developing countries to develop a theoretical body of PPP knowledge for future research.