We report two experiments demonstrating that visual word recognition is impeded by the presence of nearby stimuli, especially adjacent words. Reading research has converged on a consensus that skilled readers control their attention to make use of information from adjacent (primarily upcoming) words, increasing reading efficiency. Other lines of research seem to point to potential interference from nearby items, yet this has not been investigated at the critical lexical level. To specifically target lexical activation, here we employ a novel variant of the visual world paradigm with masked (75 ms) flanked visual word targets, contrasting five flanker conditions across two experiments, namely none, repeated symbols, unknown font strings, pseudowords, and words. Analysis of multiple observed variables from 60 and 58 adult Norwegian speakers showed strong interference—compared to no flankers—for all flanker conditions except the repeated symbols. Interference increased with additional levels of possible flanker processing, and was greatest for higher-frequency word targets, consistent with rapid dynamic modulation of attentional breadth. Our findings demonstrate that nearby words interfere with lexical activation of the fixated word and call for a more nuanced approach to the role of preview in fluent reading. We conclude that skilled reading involves a constant complex interplay between the drive toward efficiency, which requires a broad attentional field, and the need to shield processing from interference, which limits attentional breadth.