PARIS (By Katrin Bennhold and Bowley, NYTimes) May 16, 2007 — Nicolas Sarkozy was officially inaugurated as France’s 23rd president today, vowing to bring far-reaching change, but also order and authority, to his country. He then left for Germany to meet with German Chancellor Angela Merkel.

In a highly ritualistic handover of power, Mr. Sarkozy was met on a red carpet at the Élysée Palace by the outgoing president, Jacques Chirac, his former mentor and bitter political rival. In a brief private meeting, Mr. Chirac turned over the country’s secret nuclear weapons codes to his successor.

After Mr. Chirac drove off into private life, Mr. Sarkozy was greeted in the palace’s grand ceremonial hall by his wife, Cecilia, and their children, and by a gathering of the French political, business and intellectual elite, including some figures who are likely to be ministers in Mr. Sarkozy’s government.

In his first speech as president, Mr. Sarkozy said he had a mandate for change in France.

“The people have given me a mandate and I will fulfill it,” he said.

Mr. Sarkozy, who handily defeated his Socialist opponent, Ségolène Royal, in a runoff election earlier this month, said that people in France were demanding a break with the past, “because never before has the opposition to change been so dangerous for France as in this fast-moving world.”

The speech reflected many of the promises he made during the election campaign, when he portrayed himself as a man of action ready to shake up France.

Mr. Sarkozy has already broken with the past by offering some cabinet positions to the opposition Socialists. Mr. Sarkozy’s foreign minister is expected to be Bernard Kouchner, the founder of the Nobel Prize-winning organization Médecins Sans Frontières and an iconic figure of the left. Though a Socialist, Mr. Kouchner is known for his Atlanticist outlook, and was one of the few influential figures in France who did not oppose the American-led invasion of Iraq.

On Thursday, the new president is expected to appoint François Fillon as prime minister.

Mr. Fillon is a former social affairs minister who oversaw a controversial pension overhaul in 2003 and has good relations with labor unions, which will be important for overseeing Mr. Sarkozy’s promised economic modernization of France.

Mr. Sarkozy has already met with leaders of the biggest labor unions to discuss his plans for economic change; on Tuesday, he began consulting with leaders of opposition parties.

The remaining 15 cabinet ministers are expected to be named as soon as Friday, and the group is expected to include at least seven women; one ally of Mr. Chirac; two centrist politicians; and possibly another Socialist.

After an election campaign that was unabashedly rightist in tone and won him a reputation for blunt language and controversial proposals, Mr. Sarkozy’s determination to include opponents in his government has surprised many officials and analysts, some of whom call his initiative wise, and others Machiavellian.

His apparent success in persuading Mr. Kouchner to join his cabinet has unsettled many in the Socialist Party, which is still reeling from its third successive presidential election defeat and is deeply divided as legislative elections next month draw closer.