French Sign Language (French: langue des signes française, LSF) is the sign language of deaf and hard-of-hearing people in France and in French-speaking parts of Switzerland. According to Ethnologue, it has 100,000 native signers.
French Sign Language is related and partially ancestral to Dutch Sign Language (NGT), Flemish Sign Language (VGT), Belgian-French Sign Language (LSFB), Irish Sign Language (ISL), American Sign Language (ASL), Quebec (also known as French Canadian) Sign Language (LSQ), Brazilian Sign Language (LSB or Libras) and Russian Sign Language (RSL).

French Sign Language is frequently, though mistakenly, attributed to the work of Charles Michel de l'Épée (l'abbé de l'Épée). In fact, he is said to have discovered the already existing language by total accident; having ducked into a nearby house to escape the rain, he fell upon a pair of deaf twin sisters and was struck by the richness and complexity of the language that they used to communicate among themselves and the deaf Parisian community. The abbé set himself to learning the language, now known as Old French Sign Language, and eventually he established a free school for the deaf. At this school, he developed a system he called "methodical signs", to teach his students how to read and write. The abbé was eventually able to make public demonstrations (1771–1774) of his system, demonstrations that attracted educators and celebrities from all over the continent and that popularised the idea that the deaf could be educated, especially by gesture.
The methodical signs he created were a mixture of sign language words he had learned with some grammatical terms he invented. The resulting combination, an artificial language, was over-complicated and completely unusable by his students. For example, where his system would elaborately construct the word "unintelligible" with a chain of five signs ("interior-understand-possible-adjective-not"), the deaf natural language would simply say "understand-impossible". LSF was not invented by the abbé, but his major contributions to the deaf community were to recognize that the deaf did not need oral language to be able to think, and to indirectly accelerate the natural growth of the language by virtue of putting so many deaf students under a single roof.
この頃からフランス手話は隆盛を極めましたが、19世紀後半になると、手話教育の学派と口話教育の学派の間で分裂が生じました。1880年にミラノで開催された国際聾唖教師会議では、口話教育の伝統が優先されることが決定されました。やがて手話の使用は言語学習の妨げになると考えられ、教室での使用は禁止されるようになりました。
この状況は1970年代後半までフランスでは変わらず、その後、ろう者コミュニティが手話の認知度向上とバイリンガル教育制度の実現を求めて運動を始めた。1991年、国民議会はファビウス法を可決し、ろう児の教育におけるLSFの使用を正式に認可した。2005年にはLSFを独立した言語として完全に認める法律が可決された。 [ 2 ]
フランス語の手話アルファベットは、LSFの手話を区別するためと、手話の中でフランス語の単語を取り入れるための両方に使用されます。