Friends and relatives back home often tell them they are crazy not to leave. The U.S. government virtually has disclaimed responsibility for them.

But despite the bomb attacks, the kidnapings, the difficulties of everyday living, a hard core of Americans refuses to quit this beleaguered country.

Their reasons for staying vary. Some remain out of a sense of commitment to projects underway, some for career opportunities, others out of habit or inertia.

The U.S. government declared long ago, and has reiterated many times since, that anyone without urgent business in Lebanon should not be here.

Thousands of Americans along with other foreign nationals and many Lebanese have fled since Lebanon's civil war began nine years ago, reducing what was a thriving foreign community of businessmen, academics and diplomats to a couple of hundred hangers-on.

As the security shield around U.S. diplomats and military trainers in Beirut is reinforced and the official U.S. presence here is diminished, the other Americans in the capital have been warned that terrorists will be even more inclined to strike at them as the easier targets. In addition to William Buckley, the U.S. Embassy political officer kidnaped in February, extremists continue to hold two American civilians seized this year in Beirut: Jeremy Levin, a correspondent for Cable News Network, and Benjamin Weir, a Presbyterian minister.

No exact count exists for the Americans still in Lebanon. U.S. Embassy figures released at the start of the year listed 5,000 U.S. passport holders in the country, including 1,500 in Beirut. But most of these are Lebanese-born naturalized Americans who have returned from the United States.

Native-born Americans in Beirut appear to number fewer than 200. The largest group teaches at the American University of Beirut, the Beirut University College or the American Community School, or work for U.S. media organizations. Assorted others operate as social workers, preachers, businessmen or students.

George Mead is the last American banker in a city that used to pride itself on being a center of finance in the Arab world. He arrived two years ago as a vice president of Citibank, which owned an interest in the Bank of Lebanon and Kuwait with headquarters here. Citibank sold its interest last year, but Mead remained. At 35, he is now general manager of the bank. "I don't know of any other place where a guy my age can manage a bank," he said, explaining why he stayed. He regards doing business in this fragmented country as a challenge. His bank has branches in Israeli-occupied Sidon, Syrian-controlled Tripoli and Beirut. "I'm basically running an international bank," Mead said, half jokingly.

Neff Walker, a psychologist on the American University of Beirut faculty, looks upon Lebanon as a laboratory for research on how people deal with stress. He expects that his presence here will provide added authority to his findings. "Living here lends credence to what you have to say," Walker said.

For Cary Vaughan, a young woman teaching English at the university, the departure of other foreign faculty members facilitated a rapid career rise. Last summer she served as acting chairman of the English department.

Longtime residents such as Mary Regier, who teaches mathematics at the university and has lived in Beirut 27 years, said uprooting now simply would be too difficult. Her husband, Frank, an engineering professor, was kidnaped in February but freed in April. He is spending this term in the United States but plans to return to Beirut next year.

"I knew things were going to be tough when I came here, but I hadn't expected things would be as bad as they got," said Thomas Sutherland, another of the 30 Americans on the university's 450-member staff. He chairs the agriculture department. "When I went back this summer to recruit, I met lots of friends who said they were happy to see me out of Beirut. When I told them I intended to go back, they told me I was out of my head. After about 20 people say that to you, you begin to wonder.

"We've joked, my wife and I, about whether we're sane to stay. But we've never seriously considered going. I'm here to do my job, and I'm working my butt off."

Dennis Hilgendorf runs a church-sponsored emergency relief effort, as well as programs for drug addicts and handicapped. "The reason I'm here is because there's a need for the things we're doing," he said. "Once you get committed to seeing a program through, you hate to leave."

But he, like two dozen other Americans interviewed, takes precautions. In February, when Moslem militias seized control of west Beirut, Hilgendorf moved the headquarters of his aid center from the west side of the capital to the Christian-dominated east side, considered a safer area for Americans. He also moved his wife and children to Cyprus. Nowadays, he never goes anywhere in Lebanon alone.

Many have stopped going out at night. All said they have rejected the idea of carrying weapons, worried that doing so could provoke more violence, but some senior American faculty members at the university are now shadowed by armed bodyguards. A certain level of fear is commonplace and only natural.

"I don't feel endangered by an organized group like Amal," the Shiite Moslem militia movement, banker Mead said. "My problem is the unknown. I'm worried about the splinter groups, the four- to 10-man operation that would basically ruin my day."

Referring to the time-consuming Army checkpoints that travelers crossing from one side of the capital to the other are subject to, Mead said, "What I don't like is being stuck on the Green Line dividing east and west Beirut and having to wait. That's when you start sweating small beads. Anything could happen then, and you wouldn't be able to move your car to cover."

Most appear, however, to be trying hard to keep their anxieties in check. "If you're going to sit here in fear, there's no use being here," said Catherine Bashshur, principal of the American Community School, where 15 U.S. children are enrolled.

Generally speaking, American women here feel a bit safer than the men. This is because among the more remarkable aspects of the security breakdown is that some limits still are observed. So far, no woman has been kidnaped.

Another consideration for some of the Americans left in Beirut are the feelings of Lebanese friends and associates who take comfort in seeing that not all foreigners have abandoned Beirut. "I thought when I came they needed someone with my skills," said an American teacher who arrived last year. "Now I'm not so sure. I think what's needed most is our moral support."

Not everyone, however, feels so welcome. John Cronin, the last American graduate student at the American University of Beirut, said Lebanese students regard him with mistrust and dislike. He said Moslem leaders on campus have even dissuaded other students from rooming with him.

"I can see the looks in their eyes when I pass them," said Cronin, a tall blond man easily identifiable as a foreigner. "They glare at me. They don't really appreciate my presence here. They see me as a representative of the government due to my military background."

Cronin said he spent 10 years in the U.S. Marines. He is studying for a master's degree in Middle East politics.

Concerned about the dangers of keeping U.S. citizens on staff, some Beirut-based institutions have encouraged Americans to go. A Protestant church here, for instance, severed relations with five Americans serving in its aid program.

Similarly, the board of the Near East School of Theology advised the school's American president, Ray Kiely, to take an indefinite leave. Of a dozen Americans formerly associated with the school, only Carol Weir, wife of a minister who was kidnaped and is still being held, remains.

"We're finding substitutes of other nationalities that are not so exposed to danger to teach here," said Wanis Semaan, a Lebanese who is now acting president of the theology school.

Islamic Jihad, or Holy War, the code name used by callers claiming responsibility for three car-bomb attacks on U.S. facilities in Beirut, has demanded that all Americans in Lebanon leave the country. But the American University, for one, has shown itself determined not to be intimidated by the terrorist threat.

The university is the primary symbol of America's cultural presence in the Middle East. Last month it again named an American to the dangerous job of president.

The previous president, Malcolm Kerr, was gunned down outside his campus office in January. His predecessor, David Dodge, was kidnaped and held for a year by Moslem extremists.

The new president is Calvin Plimpton, a 65-year-old physician on the school's New York-based board of trustees. His appointment was greeted with grumbling by some faculty members who had hoped for a younger man. But many were pleased that an American of such caliber was willing to take the position at all.

A common refrain in the comments of all the Americans interviewed was strong opposition to U.S. policy in the Middle East. In a written statement, Carol Weir blamed her husband's kidnaping on what she termed the lack of evenhandedness in U.S. treatment of Israel and the Arab states.

Summing up the remarks of others, a professor at Beirut University College said: "I feel that by making mistake after mistake in this part of the world, America is putting my life in danger."