理論語言學，或一般語言學，是語言學的一個分支，它研究語言本身的本質，并試圖回答語言是什么的基本問題;它是如何工作的;普遍語法(UG)作為一種領域特有的心理器官是如何運作的，如果它存在的話;它的獨特性質是什么;語言如何與其他認知過程相聯系，等等。理論語言學家最關心的是構建語言知識的模型，并最終發展成一種語言理論。一般認為理論語言學的核心領域是音系學、形態學、句法和語義學。雖然音位學常常指導音系學，但它常常與語義學一起被排除在理論語言學的范圍之外。理論語言學還包括對語言共性的解釋，即所有或許多語言都具有的共性。

Theoretical linguistics, or general linguistics, is the branch of linguistics which inquires into the nature of language itself and seeks to answer fundamental questions as to what language is; how it works; how universal grammar (UG) as a domain-specific mental organ operates, if it exists at all; what are its unique properties; how does language relate to other cognitive processes, etc. Theoretical linguists are most concerned with constructing models of linguistic knowledge, and ultimately developing a linguistic theory.The fields that are generally considered the core of theoretical linguistics are phonology, morphology, syntax, and semantics. Although phonetics often guides phonology, it is often excluded from the purview of theoretical linguistics, along with semantics. Theoretical linguistics also involves the search for an explanation of linguistic universals, that is, properties that all, or many languages have in common.