This chapter presents a mixed-methods study on how English language teaching (ELT) teacher learners conceptualise and assess task engagement, as well as the factors that promote task engagement. Semi-structured interviews revealed that teacher learners had a solid understanding of behavioural and cognitive engagement but showed a need for further development in recognising emotional and social engagement. Drawing on the interview findings, a survey was designed to investigate teacher learners’ perceptions of influential factors on task engagement across three communication modes: face-to-face communication, computer-mediated communication, and immersive virtual reality. The survey results highlighted teacher learners’ awareness of engagement facilitators across these modes. Overall, the findings underscore the importance of integrating the conceptualisation, assessment, and influential factors of task engagement into teacher education programmes, thereby strengthening teacher learners’ knowledge base and better preparing them for future practice.