Sustainability awareness is increasing globally, and consumers demand sustainable practices from companies now more than ever. The fast fashion industry, however, has faced scandals highlighting unsustainable supply chain practices. In response, several fast fashion brands have implemented transparency to influence consumers' purchasing decisions and adhere to their sustainability needs.

Thus, this thesis analyses the impact of supply chain transparency through eco-labels on fast fashion consumers in Germany, a developed nation, and Peru, an emerging country. A comparative study using interviews explores how eco-labels in the fast fashion industry influence consumer behavior, revealing national differences and similarities and contributing to Sustainable Development Goals 8 and 12.

The findings show that while German and Peruvian consumers value supply chain transparency, factors such as financial resources and sustainability awareness significantly impact eco-labels' effect on purchasing decisions. Consumers in countries with more significant financial resources and higher sustainability awareness value and desire transparency more, making eco-labels more effective. Thus, cross-nationally, eco-labels should be (1) Transparent, (2) Standardized, and (3) Simplified, while on a national level, adjustments regarding (1) Education and (2) Accessibility must be made. 

The study contributes to the existing literature by identifying the need for continued affordability in fast fashion while highlighting the need for standardizations and adaptation to successfully implement them on both a national and a cross-national scale.