Mind-wandering (MW) is ubiquitous and is associated with reduced performance across a wide range of tasks. Recent studies have shown that MW can be related to changes in gaze parameters. In this dissertation, I explored the link between eye movements and MW in three different contexts that involve complex cognitive processing: visual search, scene perception, and reading comprehension. Study 1 examined how MW affects visual search performance, particularly the ability to suppress salient but irrelevant distractors during visual search. Study 2 used a scene encoding task to study how MW affects how eye movements change over time and their relationship with scene content. Study 3 examined how MW affects readers’ ability to detect semantic incongruities in the text and make necessary revisions of their understanding as they read jokes. All three studies showed that MW was associated with decreased task performance at the behavioral level (e.g., response time, recognition, and recall). Eye-tracking further showed that these behavioral costs can be traced to deficits in specific cognitive processes. The final chapter of this dissertation explored whether there are context-independent eye movement features of MW. MW manifests itself in different ways depending on task characteristics. In tasks that require extensive sampling of the stimuli (e.g., reading and scene viewing), MW was related to a global reduction in visual processing. But this was not the case for the search task, which involved speeded, simple visual processing. MW was instead related to increased looking time on the target after it was already located. MW affects the coupling between cognitive efforts and task demands, but the nature of this decoupling depends on the specific features of particular tasks.