Extending our understanding of the interplay between visual and cognitive processes during reading is essential to understand how reading develops and changes across the lifespan. Monitoring readers' eye movements provides a fine-grained online protocol of the reading process as it evolves over time, but until recently eye movements have rarely been collected for young developing and ageing people. Developmental eye-tracking constitutes an emerging and innovative field that addresses various theoretical questions related to changes in the process of reading across the lifespan and the mechanisms that drive intra-individual trajectories and create inter-individual differences among readers. The aim of this editorial is to briefly summarise the current state of the field and to outline which questions are currently being investigated and presented in this Special Issue.