There is scant evidence of OER reuse or sharing; OER apologists maintain that reuse is happening in private spaces, but others argue there is no evidence of such 'dark reuse'. The OER lifecycle provides a model of OER engagement, defining five key practices: finding, composing, adapting, reusing and sharing. However, no empirical research has yet investigated whether teachers' engagement with OER follows this model; evidence from OER repository analytics suggests not. This paper draws on an empirical study of engagement with an OER repository by language teachers at a distance university (The Open University UK). Through the applied thematic analysis of data generated through observation of lesson preparations, the paper's contribution is to validate the OER lifecycle model and provide evidence of 'dark reuse'. Qualitative tools, sensitive to the situated nature of OER engagement, are crucial to understanding invisible practices around 'dark reuse', and sophisticated models that embrace the complexity of OER ecosystems are needed.