Interlocking directorates, defined as cross-firm board ties created when directors simultaneously hold seats across multiple organisations, represent a theoretically contested governance mechanism whose effects in unlisted family businesses remain fragmented across competing resource-bridging and agency-risk interpretations. This systematic review aims to resolve this fragmentation by developing an integrative, mechanism-based framework, the Governance Triangle, that specifies when interlocks function as resource-bridging ties versus agency-masking ties, determines the busyness tipping point at which network centrality shifts from complementing to eroding socioemotional wealth (SEW)-driven governance effectiveness, and theorises interlocks as conduits for ESG and green-governance diffusion into unlisted family firms. Following PRISMA 2020 guidelines, a systematic search of Scopus retrieved 446 records, of which 257 peer-reviewed articles published between 2015 and 2026 met the eligibility criteria. Structural Topic Modelling (STM), with K = 3 topics and publication year as a metadata covariate, was applied to the full corpus of abstracts, generating document-topic proportions, FREX-weighted vocabulary profiles, and temporal prevalence trajectories for each theme. Three theoretically coherent channels emerged from the corpus: the Resource Bridging Channel (26.5% of documents), the Monitoring and Governance Channel (31.1%; the fastest-growing strand), and the Sustainability and Legitimacy Channel (42.4%; the corpus’s dominant ambient discourse). The Governance Triangle framework synthesises these findings into three propositions: interlocks facilitate governance professionalisation through resource bridging, enhance SEW-conditioned performance subject to a busyness threshold, and drive ESG integration through a green-pipeline knowledge-spillover mechanism. These findings offer an integrative theoretical account of board network effects in unlisted family businesses and establish a mechanism-based agenda for future empirical research.
Interlocking directorates, defined as cross-firm board ties created when directors simultaneously hold seats across multiple organisations, represent a theoretically contested governance mechanism whose effects in unlisted family businesses remain fragmented across competing resource-bridging and agency-risk interpretations. This systematic review aims to resolve this fragmentation by developing an integrative, mechanism-based framework, the Governance Triangle, that specifies when interlocks function as resource-bridging ties versus agency-masking ties, determines the busyness tipping point at which network centrality shifts from complementing to eroding socioemotional wealth (SEW)-driven governance effectiveness, and theorises interlocks as conduits for ESG and green-governance diffusion into unlisted family firms. Following PRISMA 2020 guidelines, a systematic search of Scopus retrieved 446 records, of which 257 peer-reviewed articles published between 2015 and 2026 met the eligibility criteria. Structural Topic Modelling (STM), with K = 3 topics and publication year as a metadata covariate, was applied to the full corpus of abstracts, generating document-topic proportions, FREX-weighted vocabulary profiles, and temporal prevalence trajectories for each theme. Three theoretically coherent channels emerged from the corpus: the Resource Bridging Channel (26.5% of documents), the Monitoring and Governance Channel (31.1%; the fastest-growing strand), and the Sustainability and Legitimacy Channel (42.4%; the corpus’s dominant ambient discourse). The Governance Triangle framework synthesises these findings into three propositions: interlocks facilitate governance professionalisation through resource bridging, enhance SEW-conditioned performance subject to a busyness threshold, and drive ESG integration through a green-pipeline knowledge-spillover mechanism. These findings offer an integrative theoretical account of board network effects in unlisted family businesses and establish a mechanism-based agenda for future empirical research.
