Mauricio Macri has been sworn in as Argentina's new president,vowing to unite the nation.
The centre-right Mr Macri took the oath of office in Congress but his inauguration was boycotted by his predecessor, Cristina Fernandez de Kirchner, in a row over the venue.
In his inaugural speech, Mr Macri vowed to tackle corruption, poverty and drug trafficking.
He also pledged "team work" and an end to confrontation in politics.
Mr Macri, 56, told Congress: "As president I want to be a citizen who can communicate with all Argentines.
"Politics for me is not a competition to see who's got the bigger ego. It's working together for the good of the people."
He vowed to work "tirelessly for you in these coming four years".
Late on Wednesday, Ms Fernandez had bid farewell to supporters in an emotional speech, urging people to take to the streets if they felt betrayed by the new centre-right government.
This is the first time since the end of the military dictatorship in 1983 that a president has not attended the inauguration of a successor.
Mr Macri triumphed in last month's election run-off, beating Ms Fernandez's chosen successor, Daniel Scioli.
Mr Macri has promised to move from a largely state-controlled economy under the leftist Ms Fernandez to one that is more free market-orientated, easing trade and currency controls.
He has also promised to improve relations with the US.
In his speech in Congress he said: "We've got to take confrontation out of the centre of politics. With fighting no-one wins, with dialogue, everyone wins.
"A new time is coming, a time of dialogue, a time of teamwork."
He said those who had voted for him wanted three goals - zero poverty, an end to drug trafficking and the unity of all Argentines.