Almost fifteen years have passed since the publication of the National Research Council's seminal report "Preventing Reading Difficulties in Young Children," which provided research-based recommendations on what could be done to better position students in pre-kindergarten through third grade for success in grade four and above. This article by Nell Duke and Meghan Block first examines whether specific key recommendations from the report have been implemented in U.S. classrooms. They find that recommendations regarding increased access to kindergarten and greater attention to and improvement of students' word-reading skills have been widely adopted. Others have not. Vocabulary and comprehension, long neglected in the primary grades, still appear to be neglected. Contrary to the report's recommendations, attention to building conceptual and content knowledge in science and social studies has actually decreased in the past fifteen years. In other words, the easier-to-master skills are being attended to, but the broader domains of accomplishment that constitute preparation for comprehension and learning in the later grades--vocabulary knowledge, comprehension strategy use, and conceptual and content knowledge--are being neglected. Near stagnation in fourth-grade students' comprehension achievement is thus unsurprising. The authors then turn to research and reviews of research on improving primary-grade reading published since 1998, when "Preventing Reading Difficulties" was issued. They discuss several instructional approaches identified as effective in improving word-reading skill, vocabulary and conceptual knowledge, comprehension strategies, and reading outside of school; they discuss advances in interventions for struggling readers, and in whole-school literacy reform. Duke and Block then identify three key obstacles that have prevented widespread adoption of these best practices in teaching reading. The first obstacle is a short-term orientation toward instruction and instructional reform that perpetuates a focus on the easier-to-learn reading skills at the expense of vocabulary, conceptual and content knowledge, and reading comprehension strategies. The second is a lack of expertise among many educators in how to effectively teach these harder-to-master reading skills, and the third is the limited time available in the school day and year to meet unprecedented expectations for children's learning. Policy makers, the education community, and parents must attend to these three challenges if they wish to see meaningful improvements in the reading skills of American children. (Contains 1 table and 61 endnotes.)