The Spanish referendum on the ratification of the proposed Constitution of the European Union presented a critical moment in the country’s participation in the European integration process. Voters were asked to approve a document that aimed to enhance the EU's governance and strengthen citizens’ rights. The proposed constitution sought to streamline decision-making in the expanding union and enshrine fundamental rights, thus making EU entities more effective and accountable to citizens.

On the day of the referendum, Spain became the first country to allow public voting on this constitutional text. The government, led by Prime Minister José Luis Rodríguez Zapatero, actively campaigned for a 'Yes' vote, emphasizing the benefits of the constitution for Spain and the broader European community. Ultimately, the constitution received significant support, with 76% of voters in favor, indicating robust approval from those who participated.

However, this positive outcome was contrasted by a low voter turnout of around 42%, raising concerns about public engagement and the legitimacy of the mandate. Critics pointed out that apathy towards the EU and lack of awareness about the constitutional details might have contributed to this turnout. Despite the encouraging majority, the outcomes prompted discussions on how to better engage citizens in European matters going forward.