This chapter presents a methodological review of task engagement research and explores how task engagement has been operationalised. It begins by reviewing how learner engagement has been measured in L2 contexts, before narrowing the focus to the assessment of each dimension of task engagement. The chapter then discusses current methodological trends, emerging directions and innovations, and the implications of these findings. The review highlights the range of methods used to assess task engagement and calls for further research that captures the dynamic nature of engagement, including the use of psychophysiological measures and longitudinal designs.