Blended learning has become increasingly frequent at the university in the past 20 years in higher education, and language learning is no exception (Nissen, 2014: §2). Literature concerning blended language learning is now extensive (see for example Neumeier, 2005, Nicolson et al., 2011, Farr & Murray, 2016, McCarthy, 2016) and provides for a wide range of analyses. Definitions of blended learning often include « a mix of face-to-face and distance learning, with both elements being an important part of the whole » (Sharma & Westbrook, 2016: 320), as well as e-learning. It is also often highlighted that blending a course considerably complexifies the learning and teaching processes (Garrison & Kanuka, 2004: 96, Nissen, 2019: 14-17). Blended language learning is specific in that because language is both the objective and the means of teaching and learning, language blended courses are often characterized by active participants, strong interactions, a great diversity of resources and is often set in the tradition of « learning to learn » (Nissen, 2019 : 12). The present contribution consists in shedding a new light on blended learning thanks to a systemic approach. We argue this approach is particularly appropriate to understand complex research objects such as blended language learning training courses. We aim to demonstrate that it was instrumental in all the steps involved in an action-research, in setting up and evaluating an English training course at the University of Lille (France) for undergraduate musicology students. With this aim in view, we first define what is here called a systemic approach. Next, we present the way this approach was used to analyse the learning environment in which the new training course was to take place. We then describe the new blended training course which was designed based on the results of the needs analysis. To finish, we evaluate the blended system and discuss to what extent the systemic approach was relevant to understand this aspect of the training course.