In 2009, the U.S. Institute of Education Sciences (IES) allocated $120 million to establish the Reading for Understanding (RfU) initiative. This initiative responded to concern that children's improvement in reading comprehension had leveled off over the previous few decades, coupled with the observation that research on reading comprehension had sufficiently matured to warrant a major investment in improving student performance. The RfU initiative involved a research and development network of six interconnected teams focused on improving reading comprehension for students in pre-kindergarten (pre-K) through grade 12. The "Reaping the Rewards of the Reading for Understanding Initiative" report articulates findings and common themes concerning the nature and development, assessment, and the enactment of curriculum and instruction of reading comprehension. It synthesizes work both within and across the six research teams, reviewing over 200 scholarly articles from this substantial and unprecedented effort to determine what has been learned about understanding and improving reading comprehension. Key findings include: (1) the importance of emphasizing comprehension in pursuit of knowledge and insight; (2) redoubling efforts to enhance language development, both oral and written, for students across the age-span; and (3) changing the culture of classrooms to emphasize collaboration, deep comprehension, critique, and the generative use of comprehension.