Abstract
This study investigates the barriers to adopting sustainable business practices among micro and macro small and medium-sized enterprises (SMEs) in the United Kingdom. Recognising the critical role SMEs play in achieving national and global sustainability goals, this research distinguishes between micro SMEs (fewer than 10 employees) and macro SMEs (50–249 employees) to explore how business size influences the challenges they face. Using a secondary data approach, the study synthesises insights from academic literature, government publications, industry reports, and sustainability frameworks to identify key obstacles such as limited financial resources, insufficient knowledge or expertise, lack of strategic planning, and regulatory complexity. The analysis reveals that while both micro and macro SMEs encounter common challenges, micro enterprises are disproportionately affected by resource constraints and capacity limitations, whereas macro SMEs often struggle with integrating sustainability into larger operational structures and supply chains. The findings offer valuable implications for policymakers, support organisations, and business leaders, and provide evidence-based recommendations to facilitate more inclusive and effective sustainability adoption across the UK SME landscape.