Although skilled return migrants are structurally positioned as cross-border brokers to conduct knowledge transfer from abroad to their home countries, they do not systematically do so. Using an original dataset of 4,183 former J1 Visa holders—all of whom worked in the U.S.—from 81 different countries, I argue that returnees' knowledge transfer success depends on their embeddedness in their home and host country workplaces and the evaluation of the knowledge recipients in their home country organizations. I find that not only do host and home country embeddedness increase knowledge transfer success, they also interact positively. However, at the organizational level, the presence of other returnees in a home country workplace decreases the positive effect of a returnee's host country embeddedness whereas the compatibility of a returnee's industry background increases it. At the country level, high xenophobia in a given home country diminishes the positive effect of host country embeddedness while increasing the positive effect of home country embeddedness. These findings inform an interpersonal perspective on knowledge transfer and contribute to work on organizational learning, employee mobility, and the globalization of expert knowledge.