This introductory paper provides the theoretical groundwork for the empirical papers which follow. The paper examines the theory of practice architectures (Kemmis & Grootenboer, 2008; Kemmis et al., 2014), a site ontological theory that attends to the composition of practices and the interconnectedness between the dimensions of language, work and power which hold education practices in place. It examines key concepts from practice architectures theory deployed in the subsequent papers including: practices, practice architectures, ecologies of practices, sites and niches.Given that the symposium explores how new workspaces intersect with changing patterns of educators’ work and their learning, the choice of a practice architectures lens is particularly appropriate. The theory’s key focus lies in theorising educational change and transformation. In order to change practices, one needs to understand the specific practice architectures or conditions that hold certain practices (sayings, doings and relatings) in place in varied sites, and which render specific practices more or less possible. A further aspect of understanding how change occurs lies in not only understanding what constitutes the enabling conditions of possibility for practices to be realised in a specific site, i.e., the ‘niche’, but also whether and if so, how, particular practices may connect up with one another in ecologies of practices (Kemmis et al., 2012). Only if such connections occur can new practices be fostered and sustained over time. As such, the theory of practice architectures provides a helpful lens through which to understand how new built environments enable and constrain educators’ professional learning practices in a range of sites including Australian and international schools and universities.