  Citation: Vale, J.; Miranda, R.; Azevedo, G.; Tavares, M.C. The Impact of Sustainable Intellectual Capital on Sustainable Performance: A Case Study. Sustainability 2022, 14, 4382. https://doi.org/10.3390/ su14084382 Academic Editors: Paula Benevene, Michela Cortini, Barbara Barbieri, Maria Luisa Farnese and Ilaria Buonomo Received: 28 February 2022 Accepted: 4 April 2022 Published: 7 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). sustainability Article The Impact of Sustainable Intellectual Capital on Sustainable Performance: A Case Study José Vale 1, * , Rafaela Miranda 2 , Graça Azevedo 3,4 and Maria C. Tavares 3 1 CEOS.PP—Centre for Organisational and Social Studies of Polytechnic of Porto, Porto Accounting and Business School, Polytechnic Institute of Porto, 4465-004 Porto, Portugal 2 Porto Accounting and Business School, Polytechnic Institute of Porto, 4465-004 Porto, Portugal; rafaela.f.miranda@hotmail.com 3 Higher Institute of Accounting and Administration of University of Aveiro, University of Aveiro, 3810-193 Aveiro, Portugal; graca.azevedo@ua.pt (G.A.); mariatavares@ua.pt (M.C.T.) 4 Center for Research in Accounting and Taxation, Polytechnic Institute of Cávado and Ave., 4750-810 Barcelos, Portugal * Correspondence: josevale@iscap.ipp.pt Abstract: Intellectual capital (IC) has become one of the most valuable resources of an organisation. Along with the increasing concerns for sustainable practices, a new concept has emerged: Sustainable IC (SIC). However, research on SIC is scarce, especially when addressing its relationship with sus- tainable organisational performance. Through a case study conducted on a small- and medium-size industrial orthopaedic footwear organisation, we aimed to assess how an organisation’s internal stakeholders perceive the concepts of SIC, sustainability, and sustainable performance and to compre- hend better the effect of SIC on the economic, social, and environmental dimensions of sustainable organisational performance. Evidence suggests that the stakeholders were not familiar with the SIC concept and overemphasised the environmental dimension when referring to both sustainability and sustainable performance concepts. Furthermore, it was found that the organisation’s sustainable performance was affected by all its SIC components (human, structural, and relational). This study contributes to the development of two different but complementing areas of research: IC and sustain- ability. It also provides important managerial implications for industrial organisations concerned with their performance. Finally, generalisation for other situations should only be conducted in a theoretical fashion. Keywords: intellectual capital; sustainability; sustainable intellectual capital; sustainable perfor- mance; SME; case study 1. Introduction In the so-called modern knowledge economy, intellectual capital (IC) has been playing a crucial role in the business, institutional, and academic fields, helping the transition towards innovative, competitive, and sustainable organisational development. In broader terms, IC can be defined as the set of skills pertaining to an organisation’s employees, which, together with the organisational structure and the relationships with stakeholders, can express with some degree of reliability the organisational potential for value creation [1]. Thus, IC encompasses people and their capabilities (human capital), organisational cul- ture and technology (structural capital), and relationships (relational capital), allowing organisations to obtain competitive advantages [2–4]. Intellectual capital is closely related to knowledge management, which can foster organisational sustainability in different dimensions (social, economic, and environmental). Consequently, it leads to the development of production systems that respect the natural and social balance of the global ecosystem [5]. Intellectual capital management can pro- mote corporate sustainability activities. Its potential contribution to solving social and Sustainability 2022, 14, 4382. https://doi.org/10.3390/su14084382 https://www.mdpi.com/journal/sustainability