The ability of Top Management Teams (TMTs) to reflect critically on their own actions represents an important element of effective TMT decision making and governance effectiveness. This paper therefore examines how the TMT-board interface internal to the organization, as well as the TMT interface with the external supervisory authority, shape TMT reflexivity. Drawing from governance and psychological theories, we posit that cognitive conflict at the TMT-board interface can escalate by increasing levels of affective TMT-board conflict, and hereby, harm TMT reflexivity if not managed well. This proposition was tested in a multisource team-level data set collected in the field among TMTs (N = 111 TMT members) and their supervisory boards (N = 152 board members) of 56 Dutch insurance companies. The findings demonstrate that the link between cognitive and affective TMT-board conflict is mitigated by board membership influx. Yet in cases where conflict escalation does occur, its subsequent impact on TMT reflexivity hinges on the degree to which an external supervisory authority monitored TMT actions. The results illustrate that TMT decision making processes can be effectively influenced by internal and external TMT-governance interfaces, yet at different conflict stages, and through different governance actions.