The founders were seen as progressives who wished to rebel against bourgeois and conservative literary and artistic circles of Brussels.
In reality l'Essor had no real program and would eventually encompass artists from the avant-garde and the more conservative circles.
When changing the name to l'Essor, Emile Hoeterickx, Julien Dillens, Amédée Lynen and Auguste-Ernest Sembach joined the group.
Gradually, other artists joined l'Essor including Fernand Khnopff (a first time participant in a l'Essor exhibition in 1881), Frantz Charlet, James Ensor, Darío de Regoyos, Albert Baertsoen, Frans Van Leemputten, John Mayne, Théo van Rysselberghe, Willy Schlobach, Guillaume Vogels, Léon Frédéric, François-Joseph Halkett, Peter George, Adolphe Hamesse, Alexandre Hannotiau, Léon Houyoux, Antoine Lacroix, Charles Goethals, Marie de Bièvre, Ernest de Bièvre, Jan Toorop and Agapit Stevens.
This dissatisfaction has come primarily from the fact that l'Essor had no real program and welcomed both realistic and traditional artists than avant-garde.