Innovation processes within corporations increasingly tap into international technology sources, yet little is known about the relative contribution of different types of innovation channels. We investigate the effectiveness of different types of international technology sourcing activities using survey information on German companies complemented with information from the European Patent Office. German firms with inventors based in the United States disproportionately benefit from R&D knowledge located in the United States. The positive influence on total factor productivity is larger if the research of the inventors results in coapplications of patents with US companies. Moreover, research cooperation with American suppliers also enables German firms to better tap into US R&D, but cooperation with customers and competitors does not appear to aid technology sourcing. The results suggest that the “brain drain” to the United States can have upsides for corporations tapping into American know-how.