In this article we develop a network-ecology approach in which we argue that the position of an organization vis-a-vis other organizations in an external hierarchy — its status or prestige — affects the level of social similarity in its employees’ professional work ties. We test our argument using data on over 85,000 lawyers employed by 303 of the largest U.S. law firms. Dyadic and concentration-ratio analyses support our predictions. We find that lawyers’ work ties have a greater level of social similarity on an important basis — shared alumni affiliations — at less prestigious law firms than at more prestigious ones. We close with implications of this study for literature on social networks, organizations, and careers.