The purpose of this study was to assess the effects of story novelty (active verbs, less familiar characters, vivid adjectives, and surprising story endings) on the reading comprehension of 48 seven- to 11-year-old boys without clinical diagnoses of learning disabilities. The optimal stimulation theory provided the basis of the study, predicting differential response to novelty by 3 groups of equivalent-IQ boys, who were at risk for reading disabilities (RD; n = 16), at risk for attention-deficit/hyperactivity disorder (ADHD; n = 16), and typically developing (n = 16). Across conditions, the RD group performed worse than typical students in the comprehension of individually graded passages and worse than the ADHD group in causality comprehension. More important, the predicted interaction in support of theory documented better reading performance in the high- than the low-novelty condition for both at-risk groups and, specifically, in causality and inferential comprehension. In other words, it was the low-novelty reading condition that exacerbated group differences in reading comprehension. The novelty-based gains were interpreted as byproducts of increased student activation, facilitating attention for the at-risk ADHD group, who have a greater need for stimulation (novelty), and for students at risk for RD to combat fatigue associated with skill deficits. (Contains 3 tables, 2 figures and 2 footnotes.)