Massive open online courses (MOOCs) offer an exciting range of opportunities to widen access and participation in education. The massive and open nature of MOOCs places the control of learning at the discretion of the learner. Therefore, it is essential to understand learner behaviour. This paper examines the psychological considerations inherent in learning and explores the psychological determinants of learner behaviours relevant to MOOCs. A number of psychological challenges specific to the development and use of MOOCs such as the motivational, emotional and intellectual commitment of MOOC learners, and the skills profile that effective MOOC learners require are discussed. The psychological barriers that learners may encounter when engaging with MOOCs are identified. In doing so, we highlight the importance of considering the psychosocial and cognitive profile of the learner, and provide a psychological characterisation of many of the practical and theoretical issues that inform the design, development and delivery of MOOCs. For example, digital literacy skills, individual differences in motivation and self-regulation are key learner attributes in the context of MOOC-based learning. The temporal dimension of learning is also addressed: how learners perceive time online, how this influences time spent on tasks and how this may impact on the effective use of MOOCs. Given that MOOCs are increasingly being accessed using mobile devices, the psychological challenges of mobile MOOC-based learning are explored. It is anticipated that the insights derived from a psychologically informed consideration of MOOC-based learning will serve as a catalyst for debate, discussion and future research.