Letter learning is nuanced, complex, and essential to the development of an effective literacy processing system. Forming and naming letters, rapidly differentiating between visually similar letters, and recognizing their sound correspondences are foundational to becoming a reader and writer. Indeed, control over letters affects monitoring, searching, and self-correcting in reading and writing. The authors argue for (a) assessment that monitors evolving letter knowledge, (b) instruction that is focused and brief and capitalizes on students' unique strengths and ways of knowing, and (c) isolated letter work that is balanced with the use of authentic texts. Transcripts of teacher-student interactions during reading and writing, personal alphabet books, magnetic letter sorts, and links to teacher resources illustrate how letter learning can be fostered in a variety of activity settings while ensuring student engagement and supporting overall literacy development.