Sjoestedt (-Jonval), Marie-Louise (1900–40), Irish-language scholar, was born 20 September 1900 in Saint-Thomas (département Aisne), France, where her family used to spend holidays. Her father, Erik-Valentin Sjoestedt, was a Swedish diplomat working at the Swedish legation in Paris, press correspondent for the Swedish government, and author of numerous Francophile articles. Her mother, Léonie Bernardini, of Corsican descent, wrote essays and novels. Brought up in a cultivated Parisian atmosphere, Marie-Louise, together with her sister Yvonne (later to become an artist), received her schooling at home, in Avenue Malakoff, and obtained a baccalauréat (philosophie) in July 1918. She then registered at the Sorbonne and brilliantly obtained all her degrees: licence (1920), diplôme d'études supérieures (1921), and agrégation de grammaire (1922; admitted as the first on the list). In parallel to this normal cursus, she attended many other lectures, on comparative grammar (by Meillet and Vendryes) and on Latin linguistics (by Havet and Jules Bloch) in the École des Hautes Études and in the Collège de France, and she began to study Slavonic languages at the École des Langues Orientales.
Following the advice of Antoine Meillet (a leading figure among French comparativists), she decided to specialise in Celtic and worked on a thesis between November 1922 and July 1925. The academic year 1924–5 she spent as a lecturer (on French language and literature) in TCD, but also studying early and modern Irish. She got in touch with T. F. O'Rahilly (qv), Osborn Bergin (qv), and other scholars. In July 1925 she discovered Dunquin and the Blasket Islands, Co. Kerry, where she was to return several times. Her main thesis was on the comparative grammar of the Celtic verb (more precisely, ‘Verbal aspect and nasal-infixed formations in Celtic languages’), and the secondary thesis was the edition of a Middle Irish saga from the Book of Lismore, ‘The siege of Druim Damhghaire’ (Forbuis Droma Dámhghaire) – a curious legend where the main characters are not warriors, but druids defending their respective countries by means of magic. Both were published in 1926, after a successful oral defence (8 June 1926).
On her return to Ireland in the beginning of 1926, she announced her intention to study the Irish dialect of Munster. The Irish language was the object of her first teaching: she was a temporary lecturer in Irish at the École des Hautes Études (1926–8). In 1928 she accepted a lecturership in Greek in Rennes University, and later became a permanent lecturer (maître de conferences); she was the first woman to be appointed to such a post in classics. This was the opportunity for her to contact Breton-speaking people. But soon after this appointment she was elected to a post of directeur d'études in Celtic languages at the École des Hautes Études (elected, 1929; confirmed, 1930), a post which she fully enjoyed and honoured. As a colleague of her former master Vendryes, she helped him to edit the journal Revue Celtique, and then (from 1935 on) Études Celtiques.
She spent a few summer holidays in Dunquin (1927–9, 1933 and 1936). These stays enabled her to produce one of the most original descriptions of Irish dialects: the first volume, on phonetics (1931), was inspired by the recent development of the Prague school of structural linguistics; her phonological principles are close to those of Trubetskoy. The Description d'un parler irlandais de Kerry (1938) was remarkable by its innovative systematisation. Both books applied to the Irish language the views of modern linguistics. The same could be said of all her studies on Irish: a series of articles on tense and aspect were inspired by the recent works of Gustave Guillaume on ‘chronogenesis’.
She married (July 1932) Michel Jonval, a French scholar, agrégé, a specialist in Lithuanian and Latvian; she studied Caucasian languages together with him in 1934–5 and stayed with him in Riga for a short while. Unfortunately Jonval died at the end of 1935.
Marie-Louise had many academic interests: social structures, mythology, and folklore, and also modern literatures. These interests were also an opportunity to communicate with other scholars: Dumézil, Lévy-Bruhe, Falc'hun, Bachellery. Her book Gods and heroes of the Celts gives a vivid and convincing insight on the social significance of heroic themes. She was a keen and scholarly observer of languages, but she was also a sympathetic figure to all the people she met, such as ‘Seán a’ Chóta’ (Seán Óg Mac Murchadha Caomhánach) (qv), her main informant on the Dunquin dialect. She was subject to depression, particularly after the invasion of France in June 1940. Her untimely death (suicide), on 26 December 1940, occurred soon after the arrest of her newly married second husband by the German army (oral information given by E. Bachellery). The posthumous compilation Marie-Louise Sjoestedt (1900–1940): In memoriam, suivi de Essai sur une littérature nationale, La littérature irlandaise contemporaine (Paris, 1941) contains a biography by Louis Renou (3–11), a bibliography (13–15), a photograph, a facsimile of her writing, several hommages, and an unedited article of hers on contemporary Irish literature; the obituary by Vendryes in Études Celtiques (1948) is mainly concerned with her scholarly achievements.