This study explores the generational differences in sustainability attitudes and the discrepancy between these attitudes and actual purchasing behaviour within the fashion industry. Despite growing environmental awareness, there remains a significant gap between consumers expressing concern for sustainability and their actual purchasing choices. Generation Z, born between 1997 and 2012, shows a strong tendency toward ethical consumption, yet often chooses less sustainable options due to affordability and responsiveness to trends. Meanwhile, the Baby Boomer generation, born between 1946 and 1964, appears to prioritize factors such as comfort and quality over explicit sustainability concerns. The aim of this research is to examine how various factors influence consumer behaviour and contribute to the persistent attitude-behaviour gap in fashion consumption. Through an integrated theoretical framework combining Consumer Culture Theory, Bourdieu's Theory of Practice, and the Theory of Planned behaviour, the study investigates the complex interplay of cultural, social, and psychological dynamics that shape consumption patterns. Particular attention is given to the role of perceived control in fashion choices, exploring why consumers, despite positive sustainability attitudes, often engage in unsustainable purchasing behaviours. In addition, the study analyzes the impact of social norms, social status, self-expression, trends, and other external influences on fashion-related decisions. The findings reveal that bridging the sustainability gap requires more than increasing consumer awareness. It demands structural changes that make sustainable fashion more financially accessible, aesthetically appealing, and culturally relevant. Generation Z’s ethical aspirations frequently collide with economic limitations and the influence of fast fashion, especially within digital spaces. In contrast, Baby Boomers' slower and more pragmatic fashion habits, though not always framed as sustainable, often reflect values of durability and long-term use. Addressing this generational divide calls for collaboration among industry stakeholders, policymakers, and educators to reimagine fashion systems that enable informed and meaningful sustainable choices across all age groups.