This paper provides detailed information about qualitative sampling for the "Transnational Mobility and Social Positions in the European Union" project. The sampling strategy is based on the SOEP-IAB Migration Sample survey. It is part of a sequential research design that uses various quantitative and qualitative methods to study the effect of spatial mobility on social positions and the role of social comparisons in determining how cross-nationally mobile people perceive their social positions. We describe how the quantitative part of the survey was used to create contrast groups that show different intersections of spatial mobility and social position as measured by the Erikson-Goldthorpe-Portocarero (EGP) scheme. In addition, we provide an overview of the main characteristics of these contrast groups. The section on outlook outlines further steps in this project and discusses the strategies used and the challenges faced in this mixed-methods research project.