"New occupations are pervasive and constantly alter fields. This paper studies how occupational newcomers and dominant incumbents confront the opportunities and constraints of field-level uncertainty by engaging in interprofessional coalition building. Using resource dependence theory to ground our arguments, we highlight that this type of uncertainty makes third-party ties the channel through which mutual dependence is assessed and power imbalance is regulated. We also claim that when dominant incumbents perceive field-level uncertainty around a new occupation, ties that regulate power imbalance overshadow mutual dependence considerations. Conversely, once occupational boundaries and norms are established through professionalization, the difference across types of third-party ties declines. Empirically, the paper uses the case of silk designers emerging as an independent occupation adjacent to the 18th-century silk guild in Lyon. Using archival data of 676 silk designers (1700–1788), we test the role of third-party ties in affecting the likelihood of a partnership forming between a designer and a merchant."