The study's objective was to establish a conceptual foundation on the appraisal of transport infrastructure projects in the Organization of Islamic Countries (OIC) Member States. Within this study, CSIL experts developed a comprehensive, but concise overview of preparation, content, evaluation, and approval of transport project appraisals in the OIC Member Countries, highlighting crucial issues and challenges, which OIC countries are currently facing, and major recommendations outlining how these issues can be addressed by the various players. The study also drew attention to the transport project appraisal practices in the OIC Member Countries and started a debate around the issues identified and how better to address them.