The vote in the Duma was 400 to 4, with 2 abstentions, and the enthusiasm among lawmakers showed a rare split at the highest levels of the Russian government. Several senior officials had spoken out against the ban, including some, like the foreign minister, Sergey V. Lavrov, who are known for relatively hawkish views in dealing with the United States.
Mr. Putin has said that Russia must respond to the new American law, but he has not yet expressed his view on banning adoptions outright. He will almost certainly be asked about it at a news conference Thursday.
The bill still faces two more legislative votes, and even before he decides to sign or veto it, Mr. Putin is likely to have huge sway over the bill's final form when it emerges from Parliament.
If Mr. Putin allows the bill to go forward, it will be the most forceful anti-American action of his new term, undoing a bilateral agreement on international adoptions that was ratified just this year and crushing the aspirations of thousands of Americans hoping to adopt Russian orphans. More than 45,000 such adoptions have taken place since 1999.
Image: Gavel, via Shutterstock