The CMAQ GUI is a windows-like interface that runs on Linux systems and helps the user download, compile, and run CMAQ. It is designed to be user-friendly and uses both a normal and an advanced view to better accommodate different skill levels. The GUI is divided into six basic parts and begins by downloading CMAQ and the associated libraries into user-defined directories. It then helps the user to select the compiler flags and compile the libraries. The next step is to compile the various programs that make up CMAQ. The GUI will notify the user of any error that occurs while downloading or compiling. The different options and environment variables can be set by simply choosing them from drop down menus in the interface. After compiling all programs the user can then run CMAQ from the GUI. The user also have the option to either run the CMAQ program in batch mode, running all the programs sequentially or you can run the programs individually. The latter option allows the user to make small changes in an individual program and not have to run the entire simulation over again.