After studying Philosophy at Utrecht University, Leonie le Sage obtained her doctorate at the Vrije Universiteit (VU) Amsterdam with interdisciplinary research from the faculties of Psychology & Educational Theory and Law into the development of conscience in juvenile delinquents and the juvenile justice system. After having worked as a university lecturer at the VU for four years, she has been working at Rotterdam University of Applied Sciences, Institute of Social Studies and Research Centre Urban Talent, since January 2008. In her position of research lecturer, she has been chairperson of the curriculum committee of Educational Theory; she has contributed to the drafting of the National and Rotterdam University of Applied Sciences Training Document of the Social Work study programme and, in the role of graduation coordinator, she has designed the graduating programme of the Social Work study programme together with colleagues.
As a researcher at the Research Centre Urban Talent, she conducted research into learning and family support. Currently, she is involved in a Laurensfonds-subsidised research project into an integrated family approach to poverty problems, in collaboration with colleagues Mariette Lusse, Liesbeth van Ree and 8 practice organisations.
Leonie le Sage has also been a board member of the National Training Forum for Social Work since 2018.