The Federal Transit Administration (FTA) is an agency within the US Department of Transportation (DOT). FTA requires all sponsors of specific types of major capital investment projects, that are recipients of federal funds, to prepare a Before-and-After Study (Study) for each project. The Study is designed to capture the actual and predicted outcomes of a project so that the knowledge acquired can be utilized in the prediction of the outcomes of future projects. The Study covers the period from the planning phase through design, construction, and the opening of a transit project for use by the traveling public. The Study evaluates the project outcomes across specific milestones, based on five main criteria, namely project scope, capital cost, service levels, operating and maintenance costs, and ridership. This paper will provide some insight into reasons why the Study is required, how a Study is planned and executed, and identify some essential steps for success.