This research investigates the work practices of system administrators. Using semi-structured interviews and an analysis of existing system administrator literature, we theorize that system administrators act as technical brokers who bridge two communities, the end users they support and their own technical community. We also show that system administrators, like other technical workers, rely on contextual knowledge. This knowledge is largely acquired through practice and less through formal education and certification. Through a discussion of common reactive and proactive system administrator duties, we present system administrators as broker technicians who must mediate between the end users they support and their technical community. We end with a discussion of the changing role of sysadmins as their tools and users get more sophisticated.