The occupation that began on Saturday was the second time in days that Shia cleric Moqtada al Sadr's supporters had forced their way into the legislative chamber.
Hundreds of followers of Iraqi Shia cleric Moqtada al Sadr have began a second day camped at the country's parliament.
On Sunday morning, the demonstrators marked the Muslim month of Muharram, a traditional Shia celebration, with religious chants and collective meals.
Volunteers distributed soup, hard-boiled eggs, bread and water to the protesters.
Some had spent the night inside the air conditioned building — which dates from Saddam Hussein's era — with blankets spread out on the marble floors.
Others took to the gardens, on plastic mats under palm trees.
A day earlier, they stormed the complex despite tear gas, water cannon and baking temperatures that touched 47 degrees Celsius.
They pulled down heavy concrete barricades on roads leading to Baghdad's fortified Green Zone of diplomatic and government buildings to break in.
Nearly ten months after October elections, Iraq is still without a new government despite intense negotiations between factions.
Analysts have said Sadr, a mercurial cleric who once led a militia against US and Iraqi government forces, is using street protests to signal that his views must be taken into account in government formation.
The immediate trigger for the occupation was the decision by a rival Shia bloc, which is pro-Iran, to pick Mohammed Shia al Sudani for the prime minister's post.
In multi-confessional and multi-ethnic Iraq, government formation has involved complex negotiations since a 2003 US-led invasion toppled Hussein.
Sadr's bloc emerged from elections in October as the biggest parliamentary faction, but was still far short of a majority.
In June his 73 lawmakers quit in a bid to break a logjam over the establishment of a new government.
That led to a pro-Iran block becoming the largest in parliament, but still there was no agreement on naming a new prime minister, president or cabinet.