This article describes the development of "Bande à Part", a mobile music application (app) for second language (L2) learners of French. Our focus on the pedagogical use of music results from the reported benefits that it offers language learners (e.g., it encourages repetitive exposure to the L2 in an enjoyable way, it extends the reach of the language classroom). In addition, "Bande à Part" has the potential to contribute to this under-researched area of L2 French pedagogy (Engh, 2013). The development of the app adopted current SLA theory and principles such as those set forth by Doughty and Long (2003). Some of these principles suggest that technology can help learners through input enhancements (e.g. grammatical gender highlighting, subtitles and translations) and grading content for proficiency level, particularly if offered in a mobile environment to foster "anywhere, anytime" learning (e.g., Stockwell, 2010). This paper introduces "Bande à Part" and the rationale for its development, including how Doughty and Long' (2003) principles were used to promote L2 learning in a mobile-assisted environment. Lastly, the current lyrical corpus is evaluated for vocabulary coverage in order to highlight the app's strengths and weaknesses according to this criterion.