Students in the 3rd and 4th grade often encounter what has been called a reading "slump" when their class curriculums increasingly ask them to comprehend and learn from texts. Students are more likely to struggle if they have not been offered sufficient opportunities to build world and domain knowledge and engage in challenging comprehension tasks while developing their reading skills. Thus, it is essential to give young readers opportunities to build their world and domain knowledge and to teach them comprehension strategies such as asking questions, paraphrasing, and self-explaining. This paper introduces iSTART-Early, an intelligent tutoring system designed to provide instruction and practice opportunities for students to learn comprehension strategies and build knowledge about diverse topics. The theoretical foundations, history and efficacy, and design of iSTART-Early are discussed.