The study examined the effectiveness of Elements of Reading: Vocabulary on improving the vocabulary outcome of third-grade students. The year-long intervention utilized a randomized controlled trial to assign teachers in Title I schools to treatment and control conditions. Teachers in the treatment condition taught Elements of Reading (EOR) which utilized explicit vocabulary instructional strategies such as semantic mapping and context clues along with other effective vocabulary development elements (e.g., oral instruction, personalization and active engagement, ample practice).