Studying social trust of immigrants and descendants of immigrants provides leverage for testing whether trust is a persistent cultural trait or, rather, a trait formed and updated by contemporary experiences. The analytical thrust comes from the fact that immigrants were born in (or, in the case of descendants, have ties with) one country, but now resides in another. If trust is a cultural trait, immigrants’ trust should continue to reflect trust in their ancestral country; whereas their trust should be aligned with trust of natives in their present country if it is shaped by experiential conditioning. In this chapter we first review studies using immigrants to study the roots of trust. Second, we critically discuss these previous studies and pinpoint a number of theoretical, methodological, and substantive shortcomings as well as avenues for addressing these in future research. Finally, we provide new empirical evidence on the roots of trust using a new dataset of immigrants from Sweden.