This essay presents an approach to developing a grammatical scope and sequence for elementary and intermediate foreign language (FL) instruction that is different from the standard model which bases the grammatical syllabus of a textbook on tradition, intuition, or both. It is argued that different descriptions of grammar are needed for each of the three skills of reading, writing, and speaking, and that a grammatical scope and sequence needs to take into account the fact that different grammatical structures are learned at different levels of development. Using the development of oral proficiency as an example, this essay then explores a research-based approach to establishing a grammatical scope and sequence. It is argued that the ACTFL Oral Proficiency Interview (OPI) forms a useful framework for interpreting findings from FL acquisition research within the context of teaching FLs in formal environments.