Professional practice is usually seen as developed and enacted within specific institutional settings. However, new forms of practice are being required which call for a capacity to work with other practitioners and draw on resources that may be distributed across systems to support one's actions. In this paper the concept of relational agency is described and illustrated with reference to a series of research studies. It is argued that relational agency leads to an enhanced form of professional agency which is of benefit to the objects of practice. The analysis is located within Cultural Historical Activity Theory (CHAT) and implications for CHAT are also discussed.