Background: Sustainability is an increasingly important topic within business administration, especially when it comes to supply chains (SCs). As members of the SC, stakeholders have the ability to influence supply chain sustainability (SCS) in various ways, regardless of industry.

Purpose: The purpose of this thesis is to explore the stakeholder influence mechanisms on the SCS of commercial laboratory testing companies.

Method: Our research consists of a qualitative case study. Primary data was collected through six semi-structured interviews within the case company and its SC, and the secondary data was collected from online databases in accordance with their relevance to the primary data and the research purpose. The data analysis process consisted of thematic analysis.

Conclusion: The results show that stakeholders can manifest their influence through various influence mechanisms, 18 in total. Customers are found to influence SCS through mechanisms of relational dependence, communication mechanisms and indirect mechanisms. Suppliers influence SCS through their own internal practices, relational mechanisms and communication mechanisms. Regulatory stakeholders influence through evolving legislation, formal agreements, strictness, certification requirements and audit processes. Top management influence evaluation mechanisms, demand mechanisms and support mechanisms. Employees influence through communication mechanisms and other influence mechanisms, while communities influence through contextual mechanisms and other influence mechanisms. These results may provide a foundation for both the commercial laboratory testing industry and academia to further research influence mechanisms in the future.