Music and online Social Network Sites (SNS) are closely intertwined in popular culture, but we know relatively little about how performers use and take advantage of such social systems. This paper investigates this space by exploring how professional DJs leverage SNS in their work. It adopts a long term mixed-methods ethnographic approach encompassing semi-structured interviews, supported by studio visits and participant observations. Results revealed that DJs used SNS for connecting to their audiences; promoting their work; receiving peer feedback; discovering content and keeping abreast of their field; and organizing and coordinating events. We further interpret our findings in the context of issues DJs highlighted about their professional practice and technology, and our observations; and draw out design implications for future music orientated systems and services.