She was president of the General Assembly of Women Students in 1935 and vice-president of the Cercle du Libre-Examen, whose mission is to promote the values of free examination, advocating the rejection of authority in matters of knowledge and freedom of judgment.

In this capacity, she led the General Assembly of Students to take a stand against measures which limited the work of married women, inspired by feminist teacher and biologist Germaine Hannevart.

[1][2][3] It was at ULB that she met and formed a lasting friendship with lawyer and later Resistance member, Andrée Grandjean.

[1] During the Spanish Civil War (1936-1939) Grégoire took a stand in favour of the Republicans and joined the Comité mondial des femmes contre la guerre et le fascisme (Women’s World Committee Against War and Fascism), one of around 2000 Belgian members.

[6] Under the code name Béatrice, Grégoire was a national deputy from October 1942 to October 1943, then responsible until 1944 for the intelligence service within the 'Armée belge des partisans, in charge of gathering intelligence to support resistance actions carried out by the Partisans against military, economic or human targets.