Does the Reader Comprehend the Text Because the Reader Is Able or Because the Text Is Easy?

Does the reader comprehend the text because the reader is able or because the text is easy? Localizing the cause of comprehension in either the reader or the text is fraught with contradictions. A proposed solution uses a Rasch equation to models comprehension as the difference between a reader measure and text measure. Computing such a difference requires that reader and text are measured on a common scale. Thus, the puzzle is solved by positing a single continuum along which texts and readers can be conjointly ordered. A reader’s comprehension of a text is a function of the difference between reader ability and text readability. This solution forces recognition that generalizations about reader performance can be text independent (reader ability) or text dependent (comprehension). The article explores how reader ability and text readability can be measured on a single continuum, and the implications that this formulation holds for reading theory, the teaching of reading, and the testing of reading.