The fastest growing city in the Balkans cascades across a barren slope forested with thousands of white tents. New residents arrive each day and a new terrace of tents goes up, each one facing the mountains that separate everyone here from Kosovo.

It is a city of people waiting to go home. "Everything I am is over there," said Abadin Mirena, who came last month with his family, except one brother who they said was shot to death by Yugoslav troops. "Once the NATO forces intervene and the Serbs leave, I will go back. All the world is trying to solve this problem, and I believe they will."

But as tens of thousands more ethnic Albanians staggered out of Kosovo last week and thousands of NATO troops were dispatched to the region with the mission of eventually resettling them, the prospects for the repatriation of 800,000 refugees are being complicated by enormous obstacles of timing, logistics and politics.

A sense of urgency is spreading among the refugees and citizens of Macedonia and Albania, the countries where most refugees are living. Families are trying to calculate when and how the conflict will end to decide whether to endure another dislocation and take refuge in a third country. Humanitarian groups and governments are studying whether to transform the precarious tent cities into more durable accommodations, while worrying that such action might signal weakening resolve to return the refugees to Kosovo.

Relief agencies have just begun planning the huge task of rebuilding camps so refugees can survive a brutal winter if a solution is not found by then. In most camps, conceived in an emergency, tents are too small for stoves, water pipes are uninsulated, and latrines will freeze with the first snow in October.

From the start, the Clinton administration and its NATO allies have made the return of all the refugees the central goal and most objective measure of success of its military campaign against Yugoslavia. The timing and extent of the repatriation have serious consequences for a variety of key participants in the Balkans crisis. In Macedonia, the continued presence of refugees could determine the outcome of presidential elections in November. For the Kosovo Liberation Army -- the ethnic Albanian rebels fighting for Kosovo's independence -- delays could make the exiles a troubled base of support. For NATO commanders, the camps could present a humanitarian disaster on the flank of a military operation -- peaceful or otherwise.

"When winter comes, who will be responsible for these people? Nobody!" said Vasil Tupurkovski, a possible contender for Macedonia's presidency. "It will be very difficult to save people in winter conditions, even more difficult than saving them from the Serbs."

Some Kosovo Albanians predict a crisis will come earlier, during a long, hot summer of confinement, or, in the case of Macedonia, in response to the hostility and fear of local authorities and a domestic population worried that the refugees will permanently alter a precarious ethnic balance.

"I don't think people will wait until September," said Baton Haxhiu, the editor of Koha Ditore, a Kosovo newspaper now being published in exile and distributed in the camps. "People will clash with police and that will be it."

Even if a diplomatic solution is reached soon, many refugees will closely examine the terms before deciding when and how to return, according to interviews over several days with Kosovo Albanians in this camp of 42,000 people and in other tent cities in Macedonia and Albania. Refugees said they would not go home if they did not feel that Kosovo had been made secure for them, and that they could not imagine a secure Kosovo without a dominant NATO force. Many also said they would rely on the KLA to tell them when it is safe to go back, providing the guerrilla force with a major source of leverage as any peace settlement unfolds.

Refugees also said that if Serbian security forces remain in the province -- or are present in any visible way at border crossings, as is now being discussed in talks by Balkan envoys -- they were unlikely to return. They uniformly rejected Russian troops as adequate on their own to guarantee the refugees' security.

"Only the ground troops of NATO, together with the KLA, would convince me," said Shaip Ramandani, 52, a school janitor from the village of Ferezai, now living in a cramped tent with a dozen relatives and seeking to find his way at least temporarily to Europe. "We have no faith in the Russians, because they are friends with" Yugoslav President Slobodan Milosevic.

Even if a settlement resolved such anxieties, the history of refugee returns offers little reassuring precedent. In most refugee crises, United Nations specialists said, a large number -- sometimes a majority -- of exiles do not go home again. They either disperse to third countries or settle in the haven that first took them in. In the Bosnian war, the return of tens of thousands of refugees who had been expelled because of their ethnic identity was also a Western goal, but resettlement remains very sparse even four years after a peace accord and despite the presence of 22,000 NATO troops in the country.

NATO commanders in the Balkans argue that if Kosovo were reconstructed with a large infusion of Western money after a settlement or a military victory, large numbers of refugees would return. Unlike in Bosnia, they said, Kosovo returnees would be moving back to a region where they would be an overwhelming ethnic majority.

Bosnia "was very difficult," said U.S. Army Lt. Gen. John Hendrix, commander of Task Force Hawk in Albania and a veteran of the Bosnian resettlement effort. "The trouble was getting ethnic cooperation. . . . Frankly, this would be easier."

Some refugees were not as optimistic.

"It was five years in the case of Bosnia, and nobody's gone back. I think that it will be like that," said Afrim Berisha, an engineer from the city of Djakovica now living in a tent city at a municipal swimming complex in Tirana, the Albanian capital. He said he would try to settle his children in Europe in the meantime, but would not go to the United States because, he said, "People who go over the ocean don't come back."

Yugoslavia's official position is that it wants all the refugees to come home as soon as possible. The government declares it never wanted them to leave in the first place and blames NATO bombing for the mass migration. But there is broad evidence from the testimony of thousands of refugees and various other sources that the government planned to smash the KLA's civilian base and to alter Kosovo's ethnic balance by systematically expelling hundreds of thousands of Kosovo Albanians. Kosovo is a province of Serbia, Yugoslavia's dominant republic.

If Belgrade accepted that the refugees were to return, would it try to manage the repatriation in a way that suits the overall goal of extinguishing the prospect of an independent, ethnic Albanian Kosovo? Exiled Kosovo Albanians fear that Milosevic would manipulate population data, property and immigration laws, and other means to limit the return flow.

"The main point of the Serbs is to block people from coming back," surmised Ylber Hysa, executive director of the Kosovo Action for Civic Initiatives. "This is why they are trying to destroy refugee documents and identities."

After 1989, when Milosevic revoked Kosovo's political and administrative autonomy, the province's ethnic Albanian majority developed a parallel government outside the official Yugoslav system. While their population at the beginning of this year was estimated at about 2 million, Kosovo Albanians did not participate in the last two official Yugoslav censuses. Milosevic "will play with the figures," Hysa predicted. "He'll say there were only 1.5 million ethnic Albanians" before the war began, and that economic migrants from Albania disguised as refugees must be kept out.

Even leaders of the democratic opposition in Belgrade seem uneasy about a full-scale return of the refugees. Some argued that a complete return would promote instability regardless of how Yugoslavia emerged from the crisis.

Full repatriation of the refugees "would fulfill your sense of justice, but I don't think it would be stable," said Predrag Simic, an adviser to Serbian opposition leader Vuk Draskovic. "Besides, I think Milosevic would fight hard against this because if he were to allow it, it would be asked, `Why did we take bombs for two months?' "

Draskovic himself worried during an interview that repatriation "could be used by Tirana to send hundreds of thousands of `real' Albanians into Kosovo as refugees." He added, though, that the problem could be managed through civil administration that included Serbian representatives, and that he was not overly concerned.

Still, this sort of talk chills exiled Kosovo Albanians, many of whom are pouring across the borders with Macedonia and Albania without passports or other official papers. Many said they were deliberately stripped of their documents by Serbian forces. Others said that in the speed of their departure or the hardship of their journey they lost whatever papers they had. Either way, there are now tens of thousands of exiles, mostly in Albania, who lack proof of their identity.

"It's a big, big problem," said Benny Otim, a legal specialist with the office of the U.N. High Commissioner for Refugees in Macedonia. In early June, with support from Microsoft Corp., Otim will help launch a new program of registration to produce U.N.-endorsed identity cards for refugees. The cards could be used for elections and other purposes after a settlement agreement, the United Nations hopes. But Otim and others worry that even with scores of computers and special software, it may be difficult to register all refugees, including those who live outside the larger camps, especially amid Albania's erratically governed civilian population.

If the refugees do return in large numbers, it will be to villages and towns that in many cases have been razed and burned beyond recognition -- 500 towns in all have been damaged, according to the State Department. Property reclamation disputes will have to be settled and reconstruction funds allocated. It's not clear what sorts of property and other civil records remain in Kosovo. Some were reportedly carted out by Serbian forces just before the bombing began. Others exist in a confused gray area between the Yugoslav government and that of the former parallel Kosovo administration.

A larger issue is what kind of society the refugees will reenter after months of atrocities, displacements and bombing. Regional governments and the refugees themselves expect the World Bank and other Western donors to fund a massive reconstruction effort once a stable peace is achieved. But rebuilt homes, roads and bridges alone cannot restore Kosovo to its prewar state.

Will justice be meted out to Yugoslav police, army and paramilitaries, and if so, who will administer it? How will the province's prewar Serbian population be accommodated? Who will control the KLA and how? Where in all of this will postwar Serbia find the breathing space it needs to finally democratize, and what will happen if its politics are further radicalized by its growing isolation?

Hysa foresees an interim phase, in which refugees are perhaps resettled first in camps resembling those in Macedonia and Albania, but on the Kosovo side of the border. Beyond that, he worries about what kind of society will emerge in Kosovo from the pieces of a world blown apart.

"The old institutions . . . the middle strata were absolutely destroyed," he said. "Even in a developed society it would be impossible to reorganize life based on the elements of a civil society."

CAPTION: As new refugees arrived at Cegrane camp earlier this month, those already there looked for familiar faces.