Vocabulary learning is an essential component of early literacy instruction. However, choosing appropriate words for instruction can be a challenge, with many resources encouraging the instruction of words that are either too easy or too obscure. This article, based on a systematic review of vocabulary interventions, presents research-based principles for choosing words to teach. The principles include teaching a variety of words rather than relying too heavily on concrete nouns, choosing "just right" words that are neither too easy nor too hard, teaching words that are useful for accessing complex text and communicating with others, and teaching words that consider the context and the needs of learners.