For the past year, Trinity College has utilized Sahana, a free and open source disaster management system, as a foundation to teach software engineering. The goals of the use of the Sahana project are threefold: to provide students with a real-world software engineering experience; to introduce students to the open-source development model; and to attract a wider variety of students into computing due to the real-world and humanitarian nature of the Sahana project. This paper discusses an approach for using open source software as a foundation to teach software engineering in a Liberal Arts environment by involving students in an ongoing, real-world project from the very beginning, allowing students with a wide range of backgrounds to participate. Results of a learning survey of a small group of students who have participated in the project are presented. The paper also provides guidance to others contemplating incorporating open source projects into their software engineering courses or curriculum.