Increasing numbers of enterprises, whether commercial, non-profit, or from the public sector, are incorporating project portfolio management in their strategic and tactical planning. Although the presence of the word "project" implies this is a project management topic, the portfolio is really about business decisions to meet business needs. The portfolio is analogous to a personal financial portfolio, which is intended to meet personal financial needs consistent with the resources and preferences of those individuals. And just as individuals use financial reports and analyses to consider various investment options, the enterprise uses an analysis called the Business Case to evaluate various project proposals for inclusion in the project portfolio. This paper discusses the typical contents of a business case and how that information is used by the portfolio decision makers.