Family firms represent a globally dominant form of organization, yet they confront a steep challenge of finding and managing competent leaders. Sometimes, these leaders cannot be found within the owning family. To date we know little about the governance contexts under which non‐family leaders thrive or founder. Guided by concepts from agency theory and behavioural agency theory, we examine the conditions of ownership and leadership that promote superior performance among non‐family CEOs of family firms. Our analysis of 893 Italian family firms demonstrates that these leaders outperform when they are monitored by multiple major family owners as opposed to a single owner; they also outperform when they are not required to share power with co‐CEOs who are family members, and who may be motivated by parochial family socioemotional priorities.