The session Wednesday cements a detente between Suu Kyi's party and the administration of President Thein Sein, which came to power last year after the nation's long-ruling army junta stepped down. Some analysts see it as a gamble in which the opposition could end up bestowing legitimacy upon a regime that needs Suu Kyi to end years of isolation from the West and get lingering sanctions lifted.
The 66-year-old democracy leader will have almost no power in the assembly, but she'll nevertheless have an official voice in the legislative branch and the chance to challenge public policy from inside the halls of power for the first time.
Suu Kyi's parliamentary debut comes after her National League for Democracy party lost its first major political battle since this Southeast Asian nation's April 1 byelection — a bid to change the lawmakers' oath.
The NLD had refused to take its seats in the assembly last week because they opposed wording in the oath that obliges legislators to "safeguard" the constitution. The party, which has vowed to amend the document because it enshrines military power, wanted the phrasing changed to "respect."
Their failure to push through even that small change, though, underscores the immense challenges ahead in a nation still dominated by the military. On Wednesday, Suu Kyi and several dozen of her party brethren chose to compromise for now — jointly reciting the oath in the capital, Naypyitaw, as the ruling party and the army looked on.
Mobbed by reporters after the ceremony, Suu Kyi said she would not give up the struggle she has waged since 1988.
"We have to now work within the parliament as well as outside the parliament as we have been doing" all along, she said.
U.S. Secretary of State Hillary Rodham Clinton issued a statement of congratulations, calling the occasion "an important moment" for Myanmar's future.
"I encourage all political parties, civil society representatives and ethnic minority leaders to work together to address challenges and seize new opportunities for a more democratic, free, peaceful, and prosperous future," said Clinton.
The legislature itself was installed after a 2010 vote that the NLD boycotted and the international community decried as a sham. Now, as a parliamentary minority occupying only a few dozen seats, the Suu Kyi-led opposition will have little power to change what it wants to change most — the constitution, which allots 25 per cent of assembly seats to unelected military appointees.
Asked if it would be awkward sitting alongside the army, Suu Kyi said she has "tremendous goodwill toward" the soldiers.
"We would like our parliament to be in line with genuine democratic values. It's not because we want to remove anybody," she said. "We just want to make the kind of improvements that will make our national assembly a truly democratic one."
Thein Sein's government has been widely praised for instituting sweeping reforms over the last several months, including releasing hundreds of political prisoners, signing cease-fires with rebels, easing press censorship and holding the April 1 byelection that allowed Suu Kyi's party to enter parliament.
But more than half a million refugees remain abroad, hundreds of political prisoners are still behind bars and fierce fighting continues with ethnic Kachin insurgents in the north. This week, Washington-based watchdog Freedom House said that Myanmar — also known as Burma — was still "not free," and the Committee to Protect Journalists ranked the country the seventh most restricted in world.
Maung Zarni, a Myanmar exile who is a visiting fellow at the London School of Economics, said Suu Kyi's ascent is "neither a game-changer nor a sign that Burma has reached the tipping point of democratic transition."
"Quite the contrary, it marks the most important victory (yet) for the regime's strategic leaders," he said.
Suu Kyi's rise to public office marks a major reversal of fortune for a woman who became one of the world's most prominent prisoners of conscience, held under house arrest for much of the last two decades. When the 1991 Nobel Peace Prize winner was finally released in late 2010, few could have imagined she would make the leap from democracy advocate to elected official in less than 18 months.
Soe Aung, a spokesman for the Thailand-based Forum for Democracy in Burma said little would change for ordinary people, but they "have much hope in her and her party."
Over the next three years, the NLD will have to decide how to navigate the run-up to national elections in 2015, which the opposition is widely expected to win by a landslide — just as it did in 1990 when the army annulled the result.
Soe Aung said Suu Kyi will use her time in parliament to "expand the space of the opposition" by working to win over the ruling party as well as the military, and trying to convince them she is not a threat.
It is a strategy of realism, he said, because Suu Kyi knows "that without the support of the (the army), they will never be able to bring about changes in the country, the genuine changes that people would like to see."
The army's representatives wield enormous power. Changes to the constitution require a 75 per cent majority, meaning that doing so is all but impossible without military approval.
Maung Zarni said the most crucial test will come in three years.
"It remains an open and serious question whether the military as an institution or the generals and ex-generals will stomach the idea — much less the reality — of a landslide by Aung San Suu Kyi and her party in 2015," he said.
"But three years is a long, long time," he added. "There is nothing irreversible about Burmese politics."
Pitman reported from Bangkok.