Course in General Linguistics (French: Cours de linguistique générale) is a book compiled by Charles Bally and Albert Sechehaye from notes on lectures given by historical-comparative linguist Ferdinand de Saussure at the University of Geneva between 1906 and 1911. It was published in 1916, after Saussure's death, and is generally regarded as the starting point of structural linguistics, an approach to linguistics that was established in the first half of the 20th century by the Prague linguistic circle. One of Saussure's translators, Roy Harris, summarized Saussure's contribution to linguistics and the study of language in the following way:

Language is no longer regarded as peripheral to our grasp of the world we live in, but as central to it. Words are not mere vocal labels or communicational adjuncts superimposed upon an already given order of things. They are collective products of social interaction, essential instruments through which human beings constitute and articulate their world. This typically twentieth-century view of language has profoundly influenced developments throughout the whole range of human sciences. It is particularly marked in linguistics, philosophy, psychology, sociology and anthropology.

Although Saussure's perspective was in historical linguistics, the Course develops a theory of semiotics that is generally applicable. A manuscript containing Saussure's original notes was found in 1996, and later published as Writings in General Linguistics.

Following a brief introduction to the history of linguistics, Saussure sets the tasks of linguistics. He largely equates general linguistics with historical-comparative and reconstructive linguistics arguing that "the scope of linguistics should be

In later parts of the book, Saussure demonstrates the limitations of the reconstructive method owing to insufficient historical data and to the unpredictability of language change. He concludes that, in order to understand why a language at a certain historical stage has the forms it has, one must also uncover the universals, which are present throughout the development of all languages. Saussure's suggestion is that the dynamic interaction of meaning and expression governs language change.

A core task of Saussure's Course in General Linguistics is to define the subject matter of general linguistics. To do this, a definition of 'language' is required. Saussure distinguishes between language (la langue) and speech (la parole) introducing his concept of the 'speech circuit' (le circuit de la parole). The speech circuit emerges when at least two persons (A and B in the picture) interact verbally. It consists of two physical elements: the brain, representing the personal-psychological aspect of speaking; and speech, which is the result of the vocal organs producing sound waves. Third, language (not visible in the picture), with its rules, arises from the speech circuit socially and historically as a non-physical phenomenon. However, Saussure considers it "concrete" and not an abstraction, making language the suitable subject of linguistics as a natural science.

The rules of language are gradually learned by the child, but adult perceptions of language vary to some degree. Saussure explains that

Beginning with the Greek word semîon meaning "sign", Saussure proposes a new science of semiology: "a science that studies the life of signs within society". However, based on William Dwight Whitney's The Life and Growth of Language (1875), Saussure emphasizes that the concept of 'life' is in this context metaphorical and not biological. Saussure does not engage in the research of any other signs than linguistic ones, but the idea of social interaction being based on sign systems was later extensively exploited by the structuralists.