This research is focused on educational and vocational guidance measures designed to support and assist young people at a disadvantage in their orientation path when transitioning to higher education. Studying this issue through the lens of Sen’s theory of social justice (1992) called for some innovative methodological approaches, including developing data collection tools and validating their scientific quality in an international comparative study (Burkina Faso, Canada, France, Switzerland and Turkey). In each study, qualitative data on the education system and the organization and delivery of guidance services were collected. In all, 26 semi-structured interviews were conducted with guidance service managers, school counsellors, as well as a number of young people transitioning to higher education. The internal validity (or credibility) of the tools was ensured throughout the development and revision of the research protocol by following each case study’s methodology. Testing the validity of the construct as well as its external validity (or transferability), starting with pre-survey data collection, has highlighted the heuristic value of the tools. Lastly, the comparative framework of educational and vocational guidance measures (included as an Appendix) is one of the first examples of operationalizing Sen’s theory in this field.