doi:10.1002/mde.70107engOrtiz, JavierGargallo-Castel, Ana F.Professionalization as a Factor of Heterogeneity in Family and Nonfamily Firms: Effects on PerformanceART-2026-149146This study examines the relationship between firm ownership and organizational performance with a focus on heterogeneity in the professionalization of management. Using a comprehensive panel dataset of Spanish manufacturing firms, the study identifies significant ownership‐ and management model‐related differences in productive efficiency. The results reveal that while family firms are marginally less productive than nonfamily firms, professionalized management substantially enhances their performance, putting it above that of professionally managed nonfamily firms. The results indicate that external management effectively addresses agency problems and mitigates asymmetrical altruism issues in family firms while simultaneously leveraging their inherent strengths, such as concentrated ownership and alignment of interests. As such, the best outcomes are achieved by combining family ownership and professionalized management. This conclusion underscores the importance of accounting for both ownership structure and heterogeneity in management models in the study of firm efficiency. Additionally, these insights have practical economic implications, suggesting that the strategic separation of ownership and management could unlock new avenues to improve organizational performance.2026http://zaguan.unizar.es/record/17107310.1002/mde.70107http://zaguan.unizar.es/record/171073oai:zaguan.unizar.es:171073info:eu-repo/grantAgreement/ES/AEI/PID2020-113338RB-I00info:eu-repo/grantAgreement/ES/DGA/S42-23R-CREVALORinfo:eu-repo/grantAgreement/ES/UZ/JIUZ2024-CSJ-03MDE. Managerial and decision economics (2026), [16 pp.]byhttps://creativecommons.org/licenses/by/4.0/deed.esinfo:eu-repo/semantics/openAccess