Making dictionaries is a vital aid to completing a full grammatical analysis of a language, particularly if the dictionary requires the specification of the part of speech for each entry. English (or “universal”) parts of speech may not be relevant in all languages, as can be shown by structural comparisons of “adjectives” in San Lucas Quiaviní Zapotec vs. Chickasaw and of “adpositions” in San Lucas Quiaviní Zapotec (and Mixtec) vs. Chickasaw. Each language will present its own structurally determined inventory of parts of speech, relevant for its own grammatical facts. Thus, discovering the actual parts of speech of a language is a critical part both of dictionary making and of grammar writing. These aspects of linguistic analysis are crucially interconnected.