The purpose of this study was to investigate why some individuals who read refutational text demonstrate conceptual change learning, whereas others do not. Middle school students were asked to complete a pretest, read a refutational text while thinking aloud, complete a posttest, and participate in an interview. The data were analyzed in two phases. In the first phase, pretest and posttest data were analyzed, which showed that readers had acquired knowledge about fitness in evolutionary biology. In the second phase, readers who did and did not demonstrate conceptual change learning were purposively selected, and their think-aloud and interview data were analyzed to explore their online discrepancy resolution strategies. Differences in conceptual change learning were related to readers' resolution strategies. Although readers in both groups were aware of the inconsistencies between their knowledge and the to-be-learned information in the text, those who demonstrated conceptual change learning were more effective at resolving these inconsistencies during reading. (Contains 2 figures, 2 footnotes, and 6 tables.)