The two pro-Western parties that were central to the 2004 Orange Revolution won enough votes to muster a slim majority of 228 seats in the Verkhovna Rada, the 450-member parliament, and have pledged to form a governing coalition.
Their main rival, led by Moscow-friendly Prime Minister Viktor Yanukovych, has the biggest faction in parliament with 175 seats. His Party of Regions lacks a coalition partner strong enough to forge a majority, but deep divisions in the Rada point to further wrangling in a nation long mired in political conflict.
The session began with lawmakers rising from their seats to listen to a legislator's oath, read out by the new parliament's senior member, and to a choir in traditional Ukrainian costumes singing a popular folk song. Each lawmaker was to sign the oath.
Ukrainian politics have been riven by a power struggle pitting President Viktor Yushchenko, swept to power in the Orange Revolution street protests against election fraud, and Yanukovych, his bitter rival in the 2004 presidential vote that sparked the demonstrations.
Yanukovych was initially declared the winner, but the Supreme Court threw out the result and Yushchenko won a new vote.
Yanukovych rebounded and became Prime Minister after his party received the biggest share of vote in March 2006 parliamentary elections, capitalizing on widespread disappointment in the slow pace of reforms and what critics said was Yushchenko's failure to deliver on his Orange Revolution promises.
The struggle reached its peak earlier this year, when Yushchenko accused Yanukovych of an illegal power grab and called the new parliamentary election, held Sept. 30.
The Rada has 30 days to form a parliamentary majority and another 30 days to form a government.