This study made use of philosophical research to make a case for the importance of understanding the issues of oppression related to the instruments used in music therapy sessions. Literature was reviewed to summarize the history of Western symphonic instruments (specifically brass instruments) and how they have been and continue to be sites of marginalization. The main findings from the literature were related to gender discrimination and indicated that the challenges women experience in brass playing are related to physical appearance, physical abilities, and representation in brass sections. Though small in number, some studies have indicated that brass instruments are also sites for issues of race and sexuality. The findings were analyzed through an approach drawn from material culture to show how instruments, as objects, influence people, the music therapy context, and the client’s social world. Suggestions for a more informed use of musical instruments included addressing social issues with clients in sessions, conducting personal research on instruments used in sessions, and exploring social issues related to instruments in supervision.