Background: The textile and apparel industry is seen as one of the most polluting industries of these times. Consumers and retailers are both considered important stakeholders in the textile supply chain. Despite that Dutch Millennial consumers are willing to buy sustainable products, there is a gap between their intention and behaviour with regard to sustainable textile products. To narrow this gap, the influencing factors on the gap need to be indicated and opportunities for retailers to be generated.  Purpose: Explore how to narrow the intention-behaviour gap of sustainable textile consumption of Dutch Millennials together with Millennial consumers and retailers.  Method: To attain the purpose, a qualitative study was conducted. An analytical framework was created to study the factors influencing the intention-behaviour gap of sustainable textiles by Dutch Millennial consumers. To gain insights, 16 semi-structured interviews have been conducted, ten interviews with consumers and six with textile retailers.  Conclusion: Price, availability, trust in a company and knowledge and information are factors from a consumer perspective that directly impact the intention-behaviour gap of Dutch Millennials. Moreover, the results show a direct impact of retailers on the intention-behaviour gap. Four opportunities are formulated to narrow this gap from a retailer's perspective.