A Rosegarden composition file (.rg) contains all of the the note information for your composition, as well as other data such as MIDI controller settings, plugin details, and the names of any audio files referred to in your composition. The audio files themselves are not stored in the Rosegarden composition file; instead you are expected to keep track of their location on disk yourself (see Audio segments). When you need to transfer a project from one computer to another, or to a friend or colleague, this can be inconvenient. This is where Rosegarden Project files are useful. A Project file contains your composition, all of the audio files it uses, any further data files required for plugins used in the composition, and any additional files you may want to include, all in one big bundle.

Use File->Export->Export Rosegarden Project file... to export the current composition and its associated data into a Rosegarden Project file, and File->Import->Import Rosegarden Project file... to expand a Rosegarden Project file back into a composition and load it.

Note that Rosegarden Project format is an interchange format, not an archival format. Although Rosegarden composition files are very carefully checked for compatibility from one Rosegarden version to the next, no long-term guarantees are made for the Project file format.