We used a design-based research model to examine a historical literacy intervention in Grade 6 classrooms. This article describes the results across 2 separate instructional cycles and for students grouped into 4 categories: (a) high-achieving students (n = 23 and n = 24 for Cycle I and Cycle II, respectively), (b) average-achieving students (n = 39 and n = 44), (c) low-achieving students (n = 17 and n = 23), and students with disabilities (n = 9 and n = 8). The findings suggest that the intervention enhanced students' ability to read historical sources and produce more sophisticated historical writing. Although comparisons of measures of reading comprehension suggest that high-achieving students outperformed students with disabilities in 2 separate instructional cycles (all ps < 0.05), students with disabilities earned comparable comprehension scores as their average-achieving and low-achieving peers in both instructional cycles; moreover, all 4 groups of learners constructed essays at posttest in the 2nd instructional cycle that were statistically similar.