The first part of this study explored the significant works pertaining to the understanding of reading comprehension using a Modified Delphi Method. A panel of reading comprehension experts identified 19 works they considered to be significant to the understanding of reading comprehension. The panel of experts identified the reasons they considered each identified work to be significant. In the second round of the Delphi, the comprehension experts rated the identified works and reasons for significance on a Likert-type rating scale. The second part of this study was a content analysis of 16 of the 19 identified significant works. The content analysis focused on concepts relevant to the understanding of reading comprehension. The concepts were used to identify themes pertaining to the understanding of reading comprehension. (Contains 7 tables.)