This thesis investigates and answers questions surrounding the professional identity of small ensemble musicians, the interpersonal relationships of the members that work within chamber music groups, and the organisational approaches to maintaining an ensemble in today's cultural environment. Specifically, this research addresses the following questions: in the current cultural environment, how is a sustainable ensemble created and how do the qualities and characteristics of musicians support the development of an ensemble? How do the interpersonal relationships between ensemble members affect the working and sustainability of the group? And, what organisational aspects must be taken into consideration as far as communication, commitment, shared values and goals? By taking the individual musician's perspective on ensemble performance and organisation within non-traditional or unconventional ensembles, this thesis aims to answer these questions through discussion provided by professional musicians working in the field. Through this process, the research highlights the opportunities and approaches available to training or practising musicians, and the skills needed for a successful career. As different genres of classical chamber music ensembles have emerged during the 21st century, the aims and output of these ensembles have developed in new and unconventional directions. This has inevitably had consequences for the professional identities of ensemble members and the musical and non-musical processes applied to their musical groups. The literature surrounding chamber music ensemble performance and processes has focused mainly on traditional ensembles, primarily the string quartet, piano trio, woodwind quintet, and vocal ensembles. These have served as examples towards investigating the cognitive, psychological and communication methods of small, high-performing teams. By focussing on non-traditional ensembles; those that have mixed instrumentation, varied members, and perform early, contemporary or new music, this research investigation explores commonalities and differences in interpersonal dynamics of non-traditional or new genres of ensembles. This contributes further understanding of ensemble processes, adding to the information provided by more traditional ensembles discussed in existing scholarly research.