This chapter provides a summary of two metacognition-based reading intervention studies among fourth graders. Since several studies suggested and documented the usefulness of teaching reading strategies, our research can be considered as an application of metacognition theory in Hungarian elementary school reading education. Our studies have the following characteristics: (a) brief intervention programs, (b) being embedded in school subjects, (c) addressing both declarative and procedural elements of metacognition in reading. Ecological validity was a central issue in these studies. In the first study, reading and mathematics training programs were applied simultaneously. In the second study, a new reading intervention program was developed aiming at gradually introducing different reading strategies and awareness of the use of strategies. The results suggest that in Grade 4 Hungarian elementary school students benefited from the explicit training of reading strategies.