By virtue of the internationalisation of economies, international student mobility is considered increasingly important for professional careers. However, most studies focus on the supply-side by using graduate surveys, which face problems of graduates' self-selection. Other studies on employers' opinions often lack rigour analysis and report ambiguous results. Combining a general matching approach with theories on human capital and sorting, studying abroad can impact both the decision on hiring and the decision on international assignment. To solve problems of endogeneity and to consider employers' perspectives directly, a vignette experiment is applied. Hypothetical applicants, with systematically varied higher education credentials, are randomly presented to a sample of German employers, in order to simulate a screening situation. Results show that study abroad experience is more important for international assignment, than for hiring. While it does not interact with final grades, it can be markedly substituted by professional work experience, when employers consider international assignment. In turn, professional work experience can be somewhat substituted by study abroad experience, when employers consider hiring. At least in the German institutional context, international student mobility may rather serve as a signal of transnational human capital, than as a signal of general job-performance.