Millions of Dutch people dressed in orange flocked to celebrations around the Netherlands Tuesday in honor of a once-in-a-generation milestone for the country's ruling House of Orange-Nassau: after a 33-year reign, Queen Beatrix abdicated in favor of her eldest son, Willem-Alexander.

At 46, King Willem-Alexander is the youngest monarch in Europe and the first Dutch king in 123 years, since Willem III died in 1890. Like Beatrix before him, Willem-Alexander has assumed the throne at a time of social strains and economic malaise.

Although the Dutch monarchy is largely ceremonial, he immediately staked out a course to preserve its relevance in the 21st century.

"I want to establish ties, make connections and exemplify what unites us, the Dutch people," the freshly minted king said at a nationally televised investiture ceremony in Amsterdam's 600-year-old New Church, held before the combined houses of Dutch parliament.

"As king, I can strengthen the bond of mutual trust between the people and their government, maintain our democracy and serve the public interest."

Hopes for the new monarch are high.

For most of the 2000s, the country was locked in an intense national debate over the perceived failure of Muslim immigrants, mostly from North Africa, to integrate. In response, politicians curtailed many of the famed Dutch tolerance policies.

More recently, this trading nation of 17 million has suffered back-to-back recessions. European Union figures released Tuesday showed Dutch unemployment spiking upward toward 6.4 percent. That's below the EU average, but a 20-year high in the Netherlands.

"I am taking the job at a time when many in the kingdom feel vulnerable and uncertain," Willem-Alexander said. "Vulnerable in their work or health. Uncertain about their income or home environment."

Amsterdam resident Inge Bosman, 38, said she doubted Willem-Alexander's investiture would give the country much of an employment boost.

"Well, at least one person got a new job," she said.

Tellingly, one of Willem-Alexander's first diplomatic missions as king will be to visit the country's largest trading partner, Germany.

While many are skeptical that the new king can make a difference where politicians have failed, the celebrations provided a welcome change from the humdrum of everyday life, and the popularity of the royal house itself is not in doubt. A poll commissioned by national broadcaster NOS and published this week showed that 78 percent support the monarchy.

The royal couple has also been active in the global campaign to fight poverty.

U.N. Secretary-General Ban Ki-moon congratulated Willem-Alexander and praised the royal couple for supporting the promotion of clean water, sanitation and development. The new king has chaired the secretary-general's Advisory Board on Water and Sanitation.

Ban also paid tribute to Beatrix for her "outstanding public service" and "for the important and positive force the Netherlands has been throughout her reign, in promoting international law, the rule of law and peaceful settlement of disputes."

Most say that the House of Orange-Nassau, which was instrumental in the Dutch war for independence in the 16th and 17th centuries, is a cornerstone of the national identity. It represents something that is both quintessentially Dutch, and above politics.

"I think (Willem-Alexander) is just like his mum — honest, wants to do a lot for his people inside the country and also outside the country," said Ron Pols, who was attending celebrations in Amsterdam.

Willem Alexander's popularity has been steadily rising since his 2002 marriage to an Argentine commoner, Maxima Zorreguieta.

In an interview shortly before his accession, Willem-Alexander turned in a relaxed performance, saying he will not be a "protocol fetishist," but a king who puts his people at ease.

Around 25,000 supporters thronged Amsterdam's central Dam Square Tuesday, hoping to catch a glimpse of the new king or the departing 75-year-old queen, now known as Princess Beatrix.

Millions more watched on television as King Willem-Alexander, wearing a fur-trimmed ceremonial mantle, swore an oath of allegiance to the country and the constitution.

Earlier, the new king gripped his mother's hand and looked briefly into her eyes after they both signed the abdication document in the Royal Palace on Dam Square.

Beatrix appeared close to tears as she then appeared on a balcony decked out with tulips, roses and oranges, overlooking her subjects.

"I am happy and grateful to introduce to you your new king, Willem-Alexander," she told the cheering crowd, which chanted: "Bea bedankt" ("Thanks Bea.")

Moments later, the generational shift was enacted symbolically. Beatrix left the balcony as King Willem-Alexander, his wife and three daughters — the children in matching yellow dresses and headbands — waved to the crowd.

The highly popular Maxima became Queen Maxima, and their eldest of three daughters, Catharina-Amalia, became the Princess of Orange, the first in line to the throne.

At a sparsely attended anti-monarchist demonstration on the nearby Waterloo Square, protestors dressed in white instead of orange and carried signs mocking Willem-Alexander.

"Monarchy is a sexually-transmitted disease," one sign said. "All animals are equal, but some are more equal than others," said another. It included a picture of a pig wearing a crown, with a line crossing it out.

Amsterdammer Jan Dikkers said he attended to show his disapproval for a hereditary head of state, and Willem-Alexander in particular, who he said Dutch people only accept because "people like his wife."

He added that Beatrix is overrated.

"People say the queen did a 'good job', but she didn't really do any job," Dikkers said.

One criticism of the royal house is that it is too expensive, especially in difficult economic times. University of Ghent professor Herman Matthijs estimates that it costs €40 million ($52 million) a year to maintain— slightly more than taxpayers' support for Britain's House of Windsor.

The difficulties facing the Dutch should be kept in perspective. Per-capita incomes remain high, the United Nations says Dutch children are the world's happiest, on average, and the country retains its triple A credit rating.

The celebrations in Amsterdam Tuesday were lively but peaceful, a stark contrast to Beatrix's investiture in 1980. Then, squatters protesting a chronic housing shortage battled police nearly to the doors of the palace.

The official festivities concluded with the new king and queen and their daughters taking an evening boat cruise around the historic Amsterdam waterfront, at one stage climbing out of their boat to join DJ Armin van Buuren and the Concert Gebouw Orchestra on stage at a concert.