International organisations' importance in education policy has been growing in recent years. They have been able to promote their role by providing data and interpreting it through international assessments and guidance, and by highlighting some countries or regions as benchmarks for global improvement, performance, and efficiency. International organisations' output feeds policy reform arguments in national and regional contexts. We analyse debates on education policy in the Portuguese parliament with the aim of understanding the roles of external references to international organisations, their instruments, and associated countries. We understand the agenda-setting process through political, problem, and policy streams as described by the Multiple Streams Approach. Our analysis shows that external references play a key role in the three streams as extra sources of authority used by policymakers in the attempt to open new policy windows and couple the three streams, resulting in policy change.