Important science about how the brain learns to read positions us to rethink some long time, intuitive assumptions about high-frequency word learning. This chapter focuses on some common misunderstandings and the reasons we might want to rethink them. Just like all tulips are flowers, but not all flowers are tulips, all high-frequency words can be sight words, but not all sight words are high-frequency words. Sight words can actually be any kind of word. They might be high-frequency words, but they do not have to be. High-frequency words—those that show up most frequently in text—are especially important for students to learn. It is common practice to describe high-frequency words as un-decodable, or irregular. Orthographic mapping is the secret sauce for moving high-frequency words into the visual word form area, eventually converting them to sight words. The chapter also focuses on a specific routine for orthographic mapping.