Confirmatory factor analyses of data from 1,501 kindergarten to 5th-grade children who completed 3 measures of decoding, 3 measures of reading comprehension, and 3 measures of listening comprehension as part of a larger study were used to identify the dimensionality of reading skills across elementary school. A 1-factor (reading) model was the best fitting model for the reading measures for kindergarten through 2nd grade, and a 2-factor (decoding, reading comprehension) model was the best fitting model for 3rd through 5th grade. Structural analyses revealed little evidence that any of the reading-comprehension measures were more or less associated with either listening comprehension or decoding than the other reading-comprehension measures, indicating that each measure assessed the same underlying construct. These results support a developmental pattern for the emergence of decoding and reading comprehension as distinctly measurable constructs, with a distinct reading comprehension construct not emerging until the 3rd grade.