Tens of thousands of protesters have taken to the streets of Madrid and other Spanish cities in a mass march against austerity measures, social spending cuts and unemployment.
Youth activists dubbed "the indignant" recently started a three-week sit-in in Madrid to pressure the government.
The rallying slogan of protesters is A Europe for its Citizens.
They fear that the Euro-pact, which is intended to improve eurozone competitiveness, will mean more cuts.
On Sunday, the protesters streamed in from all sides of the capital, chanting, banging drums and waving placards. Some walked for as long as five hours - and by early afternoon a vast crowd had converged close to parliament.
The slogans and chants are the same: against mass unemployment and social spending cuts, and in opposition to European-wide austerity measures.
"It's important to take to the streets because a series of measures are being taken by those in power - like the Euro-pact, for example - making Europe belong to the bankers and not the people," one woman protester said.
"We are all against bankers, money and capital - and against corruption and the misuse of public money. That's why we're angry," said a male demonstrator.
There is no leadership to this protest movement - it has no structure - but it does appear to have widespread social support. There are now calls to seize the momentum and stage a nationwide general strike.
In Spain, youth unemployment is more than 43%. The economic crisis has left more than a million families without a single wage-earner.
One of the main slogans along the route was "no to violence", after a demonstration in Barcelona last week ended in clashes with police.
Hundreds of extra officers have been deployed in Madrid for this march. The area around parliament itself has been sealed off as a precaution.
There are dozens more rallies taking place all over Spain this evening; and on Monday, groups from as far away as Seville and Valencia will begin a month-long march to the capital.