Sustainable production and consumption are becoming increasingly important to both consumers and businesses. Sustainability is defined as development that meets the needs of the present without compromising the ability of future generations to meet their needs. A distinction is made between social, environmental and financial sustainability, this thesis focuses on environmental sustainability in a fashion supply chain. The fashion industry has a significant impact on the environment, mostly because the textile industry relies heavily on non-renewable resources. When looking closer at the fashion supply chain, textile wet processing, which includes dyeing and printing of fabrics, contributes significantly to the environmental impact of the fashion industry by consuming and polluting significant amounts of water. Therefore, this thesis focuses on decreasing environmental impacts of textile wet processing for marlies|dekkers (MD). Fashion supply chains are highly decentralised and therefore, traceability of lacking. This leads to a lack in transparancy. Supply chain integration or supply chain alignment could overcome these challenges. The design challenge for this thesis is formulated as follows: How can a fashion company collaborate with suppliers in its supply chain to decrease the environmental impact of its textile wet processes? An analysis of the fashion industry is given, as well as a supply chain analysis and company analysis. Furthermore, suppliers and industry experts are interviewed. Finally, a collaboration strategy, that can lead to improved production processes to decrease the environmental impact of a fashion supply chain is delivered.