The UTMOST Project (Undergraduate Teaching in Mathematics with Open Software and Textbooks) is coupling the use of Sage - comprehensive free open source mathematics software - with existing free open textbooks, to make it possible for faculty and institutions to more easily bring the power of mathematics software to their students. Authors of open source software and open textbooks provide licenses that permit free copying and editing of their work, allowing others to adapt or extend them to suit their needs or make improvements. A major project activity is to convert existing open textbooks into web-based dynamic e-texts that integrate traditional mathematical exposition with Sage code and hands-on demonstrations. The intellectual merit of this project lies in its use of the innovative Sage environment and its active community of users and practitioners. Eight diverse undergraduate institutions are helping to test and refine these materials using a comprehensive, professional evaluation procedure. The main goal driving this project is to create technical and pedagogical tools and methods that greatly simplify the deployment and use of powerful software to increase learning and experimentation in undergraduate mathematics. The potential broader impacts of this project are strong given the distributed nature of both development and deployment.