The man in the street and the journalists are fond of debates about the degree and the way their language is changing. Generally, they take for granted that their mother tongue is obviously evidencing all kinds of changes: pronunciation, new words, new manners of combining them in utterances. Generally too, they evaluate negatively these changes, as they say that they are due to the bad influence of: uneducated young people, foreigners and immigrants, American imperialism, a general trend of modern societies to decay. What can be the opinion on this topic of a specialist, a linguist? We will take the case of contemporary spoken French as an example and show that a scientific approach of language change can enlighten us. First we will rely on modern linguistics achievements to distinguish changes in norms from changes in structure. And second, to further separate among structural changes: “core” from “superficial” changes.