Smartcards provide one of the best means of proving identity that is both secure and non-intrusive to the user. MUSCLE (Movement for the Use of Smart Cards in a Linux Environment) was started to quickly deploy open source software for smartcards. It provides a framework for utilizing the cards on most OS platforms including Linux, Mac OS, Solaris, Windows, etc. MUSCLE supports the Common Access Card which is the Department of Defense's cryptographic identity token. Numerous commercial products have been based off the MUSCLE code base, some of which is in use currently throughout the DoD. This presentation will aim to explain the history and background of MUSCLE. Also presented will be the MUSCLE architecture, companies and individuals who are utilizing and supporting it, and finally goals for the project.