Iraq’s parliament has approved a new government, including members of the main Shia, Kurd and Sunni parties.
However three crucial ministries – national security, interior and defence – have still not been agreed.
In a keynote speech PM Nouri Maliki said Iraqis must “denounce terrorism” and find an “objective timetable” for international forces to leave.
It is hoped the 37-minister team, the first full-term government since the 2003 invasion, can curb Iraq’s unrest.
Mr Maliki told parliament that Iraqis needed to unite in a spirit of love and tolerance.
He laid out a 34-point government programme that included tackling terrorism, integrating militias into the security structure and getting electricity and water back on line.
President Jalal Talabani, in a speech broadcast live on TV, said the new government was both a good omen and a warning.
“It provides a good omen to our people that the government will achieve for them security, stability, peace and prosperity.
“It also provides a warning to the… terrorists and the murderous criminals that the hand of justice will get them, sooner or later.”
However, the BBC’s Jim Muir in Baghdad says the new unity government got off to a messy start.
Before Mr Maliki could begin announcing his team, the leader of the Dialogue party – the smaller of the two main Sunni factions – seized the microphone to complain about how negotiations over the distribution of roles had been conducted.
Once Mr Maliki was able to speak, members of the 275-seat parliament – the Council of Representatives – applauded as each new member of the Cabinet was named and took their seat.
But then a member of the biggest Sunni faction, which is included in the government, angry about the defence and interior ministry roles being left open, led a walk-out.
Mr Maliki will for now run the interior ministry and Deputy Prime Minister Salam Zaubai, a Sunni, will run defence.
Another key post is oil minister, which has been taken by Hussain al-Shahristani, a Shia nuclear physicist jailed and tortured by former leader Saddam Hussein.
Mr Shahristani immediately vowed to crack down on corruption and the smuggling of state oil outside Iraq. He also pledged to increase production.
But with security the key issue, BBC defence correspondent, Rob Watson, says in the short term the new government is unlikely to affect what is a complex breakdown of law and order, involving Sunni insurgent groups, Shia militias and mafia-style criminality.
Just hours before the parliament began its session, at least 19 people were killed and 58 wounded in a bomb attack in a Shia district of the Iraqi capital, Baghdad.
Witnesses said that the blast in Sadr City happened at about 0700 (0300 GMT) near a food stand where day labourers seeking work were having breakfast.
In other violence, a suicide bomber killed at least five people and injured 10 in an attack on a police station in the western border town of Qaim.
Sectarian violence has spiralled in recent months. The latest cycle of attacks began with the bombing in February of a Shia shrine in the town of Samarra.
It was followed by the regular reports of the discovery of dumped bodies, bearing marks of torture and execution.
Sunni politicians said Shia death squads operating within the security forces were behind the killings.
The new unity government is the result of five months of arduous negotiations, following December’s general elections, in which the Shia alliance emerged as the largest single bloc.
It is the first to include the main Sunni Muslim factions, which had boycotted the interim elections and cabinet.