The generation, processing and circulation of data in digital form is now an integral aspect of contemporary schooling. Based upon empirical study of two secondary school settings in Australia, this paper considers the different forms of digitally-based "data work" engaged in by school leaders, managers, administrators and teachers. In particular, three distinct aspects of school data work are explored: (i) the distinction between official "mandated" data requirements from external government agencies, and the unofficial efforts to generate and work with "useful" data; (ii) the highly mediated nature of digital data work within schools; (iii) the ways in which digital data lead to compromised knowledge and "work arounds". These findings, it is argued, illustrate the embedding of digital data within secondary schools as a technology of (self)control in ways that tend to reinforce dominant cultures of school administration and management. As such, the paper considers how the restrictive forms of data governance currently at large within school systems might be problematized and acted against.