Educational researchers have invested much in isolating the specific 'drivers' that influence school change and teacher professional development. In this vein, this article draws attention to necessarily "situated" understandings of practice development through research into the nature of 'middle leading' for site based education development in one primary school district in regional Australia. Drawing on practice theory, the analysis reveals how developing and sustaining change in schools is contingent on middle leaders' insider knowledge, shared responsibility and capacity to sustain and 'drive' teachers' learning. The article argues more situated understandings of middle leading practices are essential for sustainable educational reform.