Jean-Ovide Decroly (Ronse, July 23, 1871 – Ukkel, 1932) was a Belgian teacher and psychologist.
He studied medicine at the University of Ghent, with half a year at the University of Berlin where he studied the action of toxins and antitoxins on general nutrition in 1898. He later worked with (mentally) handicapped children at the neurological clinic in Brussels.
Decroly founded The Hermitage School in 1907. He was a freemason, and a member of the lodge Les Amis Philanthropes of the Grand Orient of Belgium in Brussels. Nowadays the "Ecole Decroly" (based in Uccle, Brussels, a school reaching from kindergarten to baccalaureate) is following his pedagogical approach.
The "Decroly plan" lays ground rules for social adaptation of a biological organism, in the concrete case, children. It concludes that schooling is needed for children to meet their "biosocial needs".