This thesis explores the phenomenon of play within professional chamber ensemble music rehearsals of the Western art tradition. It sets out to provide a critical examination of existing literature on play, especially to consider relevant ideas within music performance and artistic research. The objective of this thesis was to conduct an empirical case study to investigate the perspectives of professional musicians on “play” in the chamber ensemble rehearsal context. Three studies were carried out: a focus group with practising musicians; video-recall interviews with ensemble members following rehearsal; and reflections following rehearsal by myself and independent researchers. All focus group and interview sessions were transcribed and analysed using Interpretative Phenomenological Analysis to gain an understanding of the musicians’ social constructionist experiences and perspectives on play within an ensemble rehearsal setting. The data provided insight into how play was initiated as well as the different types of play experienced within the music rehearsals, some more visible than others. An interpretation of the data revealed four key perspectives: play with the self; playing with the ensemble; playful musical interpretation; and playfulness of the rehearsal dynamic. It was noted that different types of play operated across these perspectives, including functional play, adaptive (animal) play and object play, while different kinds of play behaviours emerged, such as exploratory, spontaneous, experimental and anticipatory. There was engagement in “the game” that yielded fun and jokes along with positive emotional states and interactions. Play itself was underpinned by shared motivations, goals and knowledge of the cultural parameters of the Western art rehearsal tradition