The study (Verroens 201) is a monograph of the inchoative construction se mettre à in modern French. First, the quasi-synonymous relationship with commencer à is discussed. The aim is to describe the common and individual characteristics of both constructions and to investigate in which contexts se mettre à does and commencer à does not occur. The study reveals some limitations regarding the distribution of se mettre à. For example, it is shown that commencer à has a wider distribution syntactically, semantically and lexically and can replace se mettre à in all contexts. In a second part, the relationship to the lexeme mettre is studied and the hypothesis is put forward that se mettre à is a grammaticalized construction. In several languages, including Chinese, Japanese and Arabic, the process of grammaticalization of inchoative constructions originates in verbs meaning "to take", "to place" or "to seize". Starting from the hypothesis that we are dealing with a universal phenomenon and that the same principle therefore also applies in the Romance languages, we show how the shift from concrete spatial (mettre) to abstract aspectual (se mettre à) occurs in French. The study is innovative because of its corpus-based research and its application in the theoretical framework of grammaticalization.