At THREE in the morning, Roberto finished mopping the restaurant's kitchen and headed out into the darkness, cutting through side streets and back alleys to his basement apartment on P Street.

Even before he reached it he could see that the front door was ajar. Light was spilling out onto the steps. The chains and locks were dangling. Inside, his roommate sat in a corner, stunned and bloodied. Chairs were overturned, drawers were ransacked, closets were open and clothes were missing. It was, for Roberto, and for many other illegal aliens, a familiar scene.

This time it had been four black men and a woman. They had busted down the door as the roommate was listening to music, assaulted him, robbed the apartment of $600. There was no question of calling the police, and it would only be a matter of time before the gang would come back. Roberto and his roommate would have to move -- again.

Roberto's life is one of discipline, paranoia, and few pleasures. Living as if behind enemy lines, constantly afraid of being exposed, his only safeguard and consolation comes from "the brotherhood" of other illegal aliens.

And yet, for Roberto at least, it is worth it to be here."As a farmer in El Salvador," he says through a translator, "I was earning between $10 and $15 a month. Now I am earning $700 a month. I cannot turn down such opportunity." And it was for such opportunity that, at age 34, married with three children, Roberto mortgaged his home to pay his way to the back of a truck. From Los Angeles he flew to Washington, D.C.

Once here he went to a small shop in Southeast that he had been told about, and paid $2 for a phony social security card. "That is not so easy to do now," he says. "The government has put pressure on us." So now, every time an illegal alien returns to his country he gives his card to a member of the underground community, who will hold it for a new arrival. "It is considered a 'gift' among the brotherhood to pass on the card of opportunity." Without it there are no jobs.

Roberto, like other illegal aliens, pays federal income tax (though he lists as many dependents as allowed), and social security, though he will never collect the dividends. He mails most of his income home each month. When he finally leaves this country he wants to start his own farm in El Salvador.

On a typical day Roberto will awake -- and wait, not wanting to leave the apartment until it is time to go to work. He passes the hours watching television (though he understand very little of it) or reading books bought at a multi-lingual book store. Then he goes straight to work, keeping off the main streets as much as possible. He always arrives on time.

"We do all we can to stay on the right side of the employer," says Roberto. "If they want us to work late we will. We need the money and there is very little else for us to do."

When he can he eats in the restaurant kitchen. Other wise he will shop at supermarkets thought to be "safe," in a neighborhood where he is inconspicuous. Washington, he says, is a safer place than most cities. Many Greeks, Italians, Mexicans, and other minorities are in the position of employing aliens and are often sympathetic to their situation.

It has been a year since Roberto last saw his wife and kids, but his time in America has been profitable for him, and in December he plans to go home again, if he hasn't been turned in.

When that happens, surprisingly enough, it is often because of an argument among aliens themselves. Even the brotherhood sometimes works against them. "Every time I hear a knock at my door I think this may be it," said roberto. "But for all the worry and fear and loneliness, it is worth it. If you had ever lived in El Salvador, in a one-room house, you would understand."