BONN, DEC. 2 -- Germans from both sides of their formerly divided country today rewarded Helmut Kohl, steward of the smooth, quick route to German unity, by electing him the first chancellor of their reunited country.

Voting together for the first time since they gave Adolf Hitler's National Socialists, or Nazis, a plurality 58 years ago, Germans expressed confidence in Kohl's calm management of the historic transformation of Communist East Germany into a Western society.

Final returns showed Kohl's Christian Democrats winning 44 percent of the vote, about the same as in 1987. With the support of Foreign Minister Hans-Dietrich Genscher's middle-of-the-road Free Democrats, who won 11 percent, Kohl will lead the same center-right majority coalition that has maintained the German boom economy through even the rocky early stage of reconstructing the former East Germany.

"This is a day of joy," Kohl, 60, said tonight. "I am particularly happy that the result in the former East Germany is almost identical to that in the west. This means that in all of Germany we are the ones trusted to take responsibility."

Challenger Oskar Lafontaine, 47, the Social Democrat who tried to convince voters that Kohl was lying to them about the cost of unification, went down to a resounding defeat. The Social Democrats collected 33 percent of the vote, the party's worst showing since 1957. Voters in eastern Germany answered Lafontaine's reluctance to support unification by giving the Social Democrats only 24 percent of their votes.

Lafontaine was unrepentant in defeat, repeating his contention that Kohl committed "fraud" by failing to come clean on the soaring costs of unification. After congratulating the winner, Lafontaine said: "We will see very soon that ours was the right course. In the long run, we had the right issues. This was a generational election, and we won the support of the youth."

Kohl's coalition will control 392 of the 656 seats in the Bundestag, the lower house of Germany's Parliament, which was been expanded by 144 members to accommodate eastern Germany. The Social Democrats will hold 239 seats, the former East German Communists 17, and Alliance '90, the coalition of grass-roots groups that organized last year's East German revolution, 8.

The environmentalist Greens, who had 42 seats in the last Parliament but fell into internal bickering over German unification, suffered a crushing blow in western Germany, failing to receive 5 percent of the vote, the minimum necessary to win seats in the Bundestag.

Although Germans tell pollsters that environmental issues remain their uppermost concern, the Greens, who early this year fought against unification, lost nearly half their support in many areas of the country. "We were left behind by the . . . euphoria," said Greens leader Hans-Christian Stoebele. "The voters didn't accept our issues, but these issues won't go away."

The Christian Democrats also won municipal elections in the new capital city of Berlin, ousting a coalition of Social Democrats and Greens. But no party came close to a majority, and the two largest parties eventually may have to form a "grand coalition" to govern the city. Although the German unification treaty granted Berlin the title of capital, Bonn remains the seat of government until the new Parliament considers the question next year.

The turnout on a wet, wintry day was the lowest in postwar German history -- only 77 percent, compared to 84 percent in West Germany three years ago and 93 percent in the first free vote in East Germany this March. Leaders of most parties blamed the low turnout on Kohl's vast lead in opinion polls and the country's weariness after more than a year of historic events including, in the east, four elections in nine months.

Kohl maintained his optimism, agreeing that "there is a difficult road ahead" but insisting that the continuing boom in western Germany and the robust start to the Christmas shopping season prove "that we will succeed."

Although Lafontaine fared somewhat better in the west, where his sharp wit and affluent lifestyle did not seem so foreign, his early doubts about unification and his continuing pessimism about the cost of blending the two societies doomed his campaign throughout Germany.

By the end, the fashionable intellectual and premier of Saarland, a state near the German-French border, had so alienated even his own party that former chancellor Helmut Schmidt, a Social Democrat, said Lafontaine deserved to lose.

Kohl, the power politician who has been chancellor of West Germany since 1982, overcame his reputation for bumbling and, despite an uninspired speaking style, became a preacher of hope to 16 million grateful but frightened eastern Germans.

Seeking a third term, the chancellor made only 28 campaign appearances and never debated Lafontaine, preferring to transmit his message of optimism and patriotism through the trappings of incumbency, meeting at his weekend cottage with Soviet President Mikhail Gorbachev, President Bush and other world leaders.

While Lafontaine refused even to mouth the national hymn and rejected the term "Fatherland" as "a form of the past," Kohl led crowds in singing the anthem and rejoiced in calling unification the fulfillment of the national longing for "Germany, One Fatherland."

Kohl won his home district for the first time today; in the past he had been seated in the legislature by virtue of his standing as a party leader.

For Kohl's conservative Christian Democrats, it was the fourth electoral victory this year in eastern Germany. But this was the biggest of all, a resounding vote of confidence in a government that managed in a few months to persuade skeptical allies and a reluctant Soviet Union that the carefully constructed balance of power that had kept European peace for 45 years was obsolete and had to be redesigned immediately.

Large majorities of voters in western Germany told pollsters they do not believe Kohl's claim that unification can be brought off without painful tax increases. And many in the west are fearful that mounting unemployment in eastern Germany and political turbulence in the Soviet Union will spark immigration and economic problems that could smother the seemingly permanent German boom.

Johannes Gross, publisher of a German business magazine and a political columnist, called the vote "a ratification of German unity. Those parties who showed themselves to be hostile -- the Social Democrats, Greens and {former East German Communists} -- were punished. It wasn't at all clear what Lafontaine stood for. Was he for or against German unity?"

The Free Democrats, boosted by the leadership of Genscher, by far the most popular politician in either part of Germany, posted their strongest showing in a decade. The finish reflected Genscher's role in calming foreign fears of German unity and his lifelong and well-publicized dedication to his hometown of Halle in eastern Germany.

Analysts said the Free Democrats also benefited from the desire of some voters to choose continuity without expressing support for Kohl. Genscher's partnership in the ruling coalition is often seen as a boost for a more liberal domestic and social policy than the Christian Democrats would otherwise endorse.

Only 18 months ago, the Christian Democrats' left wing began plotting to remove Kohl as its top candidate, citing his faltering popularity and accusing him of a lack of vision. But Kohl's political savvy and control of the party quickly became clear. He dumped the party general secretary and made certain that there were no party leaders available to lead a putsch.

Then, when Kohl moved for unification with uncommon speed and certitude after the fall of the Berlin Wall, he began a year-long political tour de force that culminated last summer, when he persuaded Gorbachev to endorse German unity and begin a new era of close German-Soviet relations.

Still, as late as this April, the Social Democrats held strong leads over Kohl in opinion polls. Kohl's rise in the ensuing months stemmed not only from popular decisions such as granting East Germans a one-to-one exchange rate for their nearly worthless currency -- a virtual gift opposed by West Germany's central bank -- but also from Lafontaine's absolute inability to tap emotions released by the fall of the Wall and the end of East German communism.

After those landmark events, the election was so anticlimactic that the campaign rarely made front-page news in either part of the country. Instead, Germans remain focused on the mechanics of unification: the enormous tasks of transforming the east's economy, cleaning up four decades of environmental disaster and managing the removal of the Soviet military and other remainders of the Communist past.

But even those issues did not play a crucial role in a campaign virtually bereft of concrete proposals. The primary difference between Kohl and Lafontaine was one of perspective: Both said the coming years will bring a difficult and expensive process. But while Lafontaine portrayed unification as a trying task requiring higher taxes and massive public spending, Kohl presented it as a manageable challenge to be faced with private money and a spirit of optimism.

"Hard times lie ahead," said Lafontaine, predicting a $136 billion deficit for next year and sarcastically referring to Kohl as "our almighty one." "Roll up your sleeves."

The Kohl campaign responded with an upbeat slogan -- "Yes to Germany. Yes to the future." -- and a Hollywood-produced song consisting of positive phrases in English ("Feel the power, touch the future, reach the heart . . .").

The chancellor now must face the problems he managed to keep in the background during the campaign. Kohl hinted in recent weeks that his opposition to raising taxes to pay the annual cost of up to $90 billion for unification was wavering; he began talking of surcharges to pay for the massive environmental cleanup needed in the east.

Unemployment continues to soar in eastern Germany as industries that were once propped up by the Communist government collapse, unable to compete. The deteriorating stability of Yugoslavia and the Soviet Union threaten to turn Germany into a target of a wave of immigration unlike anything since the end of World War II.

And the standoff in the Persian Gulf is pushing the new Germany to deal sooner than any of its leaders would like with the question of what kind of global role it should play.

Kohl has said he wants a constitutional amendment giving the German military the clear right to participate in international actions such as that in Saudi Arabia. But Lafontaine and other opposition leaders won energetic cheers by arguing that unification should not mean an end to the low profile that Germany's military has kept since World War II.

The chancellor, who considers himself the most progressive leader in the drive toward European political and economic union, will now face intensified skepticism and political squabbling as he tries to persuade other countries that Germany is not seeking European integration as a means for the continent's largest economy to dominate this part of the world.