Cost Benefit Analysis (CBA) is a useful tool to assess the financial and economic implications of projects. A financial and economic CBA systematically quantifies the costs and benefits of a project, comparing them against the situation without the project. It provides an indication of how costs, benefits and project risks could be divided between project participants; and between private and public sector participants. The financial CBA takes the perspective of the project cash flows and analyses to what extent the project is attractive to private investors. The economic CBA, also referred to as socio-economic CBA, takes a wider perspective, often that of the national economy. It includes and quantifies as much as possible the external costs and benefits of the project. The economic CBA study helps decision makers decide whether a contribution from public funds is justified. In his lecture, Eric van Drunen gives a brief introduction into CBA as a project evaluation tool, and more in particular the concept of financial feasibility versus economic feasibility. He will provide a project example showing the major steps in CBA and interpretations of the results.