Attention Resolution (AR) modulation is a visual-spatial process used to isolate, in attention, a specified item in a cluttered visual display, such as the face of “Waldo” pictured in a crowd of faces or a specified letter in a written word; the speed with which AR adjustments take place is proposed to reflect AR efficiency. Children develop more precise AR with age (Wolf & Pfeiffer, 2014) enabling isolation of more-closely spaced items over time. The print size needed for optimal reading speed also decreases with age, perhaps suggesting more efficient AR modulation with practice in isolating letters during reading. Struggling readers accumulate progressively less reading exposure over time than do typical readers, and also require wider letter spacing to reach optimal reading speed, potentially indicating an efficiency-based AR deficit linked to limited reading exposure in struggling readers. AR precision and efficiency were studied in 201 children varying in reading ability in Grades 2 and 6 using a dot-tracking task. Children were asked to track and subsequently identify a target dot after it moved among visually identical distractor dots, passing the distractors at different distances (precision) and speeds (efficiency). Across grade and reader groups, relative dot-tracking accuracies across distance and speed conditions indicated additive effects of precision and efficiency manipulations on tracking performance. Reader group analyses pointed toward a general developmental delay of AR modulation in struggling readers, who performed consistently more poorly than better-able readers in their own age group regardless of distance or speed condition. Grade 6 struggling readers outperformed reading-age-matched participants in Grade 2, suggesting that chronological age was a stronger predictor of AR modulation than was reading exposure. Reader group differences are discussed in light of exploratory analyses on reading-related factors found to predict AR task performance.