In 1931 Lacasse founded Galerie l'Equipe, an open platform to young artists seeking recognition. During 1931-1937 l'Equipe was active in Lacasse's studio located 11 Impasse Ronsin, to finally open an official gallery space on the Boulevard Montparnasse, during 1937-39. Amongst the artists exhibited at Galerie l'Equipe were Sonia and Robert Delaunay, Gleizes, Picabia, Vantongerloo, Lurçat and Picasso.
During the l'Equipe period Lacasse explored the possibilities of light, space and form, sourcing from his experiences of working as a child in the stone quarries of Tournai. His ultimate search for light pushed him during 1935-36 to experimenting with spots of colour without subject or form, culminating in a series of small works, which are considered Tachist 'avant la lettre'.

The works of Lacasse are included in the following museums: Musée d'art moderne de la Ville de Paris, Paris; Musée national d'art Moderne, Centre Pompidou, Paris; Musée des Beaux-Arts, Brussels; Musée de Tournai, Tournai; Tel Aviv Museum of Art, Tel Aviv; Eilat Museum, Eilat; Carnegie Institute, Pittsburgh; National Gallery of Victoria, Melbourne.