This research investigated the cognitive demands of reading curricula from 1910 to 2000. We considered both the nature of the text used and the comprehension tasks asked of students in determining the cognitive demands of the curricula. Contrary to the common assumption of a trend of simplification of the texts and comprehension tasks in third- and sixth-grade curricula, the results indicate that curricular complexity declined early in the century and leveled off over the middle decades but has notably increased since the 1970s, particularly for the third-grade curricula.