In the study of solar-terrestrial physics there is frequently a requirement to combine and compare data from different instruments, of either the same type or of different types. This paper presents a Multi-Instrument Analysis (MIA) toolbox for Matlab. By using object-oriented programming techniques it is shown that the same tools can be applied to data from different instruments, or even instruments of different types. A coherent structure enables MIA to display image plots, keograms and movies for all imaging instruments, regardless of type. Data files are joined automatically so that file boundaries do not interrupt data processing. Although a graphical user interface is available all operations can be performed by scripts, thereby permitting automated data processing. By simplifying data processing MIA aids the creation of new data products such as energy maps and event databases. MIA currently supports riometers and imaging riometers, magnetometers and all-sky cameras.