How can one, how does one trace the contours of ‘song’? Acknowledging the elusive nature of the object ‘s essence (because of its highly disparate and heterogeneous nature), we propose to deal with the issue of the object’s delineation in a pragmatist perspective. In the first part of this dissertation, the attempt to delineate the object called “chanson” (song) encounters a series of miscellanous obstacles. The successive definitory attempts build and reproduce essentialist presuppositions (the song-in-itself) and formal standards or thematic norms which prevent them from framing the object and create leftovers. The arbitrariness of definitions found in dictionaries and books on the history of song is compounded by the heterogeneous nature of ‘chanson’ on different levels : artifact, style and situated occurrence. The use of the term “chanson” followed by a series of adjectives creates a categorization leading to a generic labyrinth dominated by a priori hierarchy and normative presuppositions. Considering “chanson” as a hypergenre (in the sense of Maingueneau) might provide a solution.In a second section, the importance of considering the different ‘moments’ of song becomes more apparent. Depending on the moment considered, the patrimonialization processes differ: the constitution of a corpus, anthologization, establishment of a repertory (repertoire). Heritage and the objects that compose it are interdependent. Exclusively institutional forms of patrimonialization, such as Fortoul’s 1852 survey or the musical folklore mission in Lower Brittany in 1939, do not construct the same object as the joint initiative of the French Museum of Popular Arts and Traditions and radio station Europe 1, to create a ‘Musée de la Chanson’ – “Song Museum” – in the early 1960s. Patrimonialization through repertory (which is the choice of ‘Le Hall de la chanson’ – "Song Hall of Fame" –, founded in 1990) would appear to be more inclusive because it is multidirectional. Unfortunately, it runs the double risk of trying to defend an objet seen as inferior and having to steer clear of the trope of the threat of extinction.In a third section, the adoption of a pragmatist perspective renders possible a dramatic change of perspective : the object is no longer seen as a semantic structure to be interpreted; rather it attains the status of “organizational object” (Garfinkel 2001). From there, the inquiry goes on to discuss song’s agency viewed in terms of its delivery in singing mode and its deployment in acting mode, firstly through the example of the constitution of a prescriptive apparatus in the context of 17th- and 18th-century Catholicism, then through the analysis of an ordinary theory developed in a treatise whose author was herself a singer : Yvette Guilbert. Two series of song-implementation trials are then examined: : those of the characterization of the object and those of a given song’s actual materialization. Finally, the ‘chanson’ object is approached from the standpoint of involving the performer’s skills and studying the pedagogical setting in which the art of song performance is handed down.