AT LAST Haiti has inaugurated a president chosen in a free and fair election -- a great moment for a country with a bitterly unhappy history. It's been a long five years since the Haitian people overthrew the Duvalier family's bloodstained regime. There have been many delays and setbacks on the road to that election, and those experiences give some suggestion of the hazards ahead for President Jean-Bertrand Aristide.

When the Duvaliers fled into exile, they left behind many Duvalierists -- people who had profited from the despotism and were by no means ready to abandon their perquisites without a struggle. They made common cause with some of the army, which in Haiti is less an institution in the modern sense than a confederation of armed bands of which many were living by smuggling and extortion. The first attempt at free elections collapsed with a massacre in which armed men shot down voters as soldiers stood by watching. Then after a succession of presidents, most of them army officers, proved themselves incapable of governing, the country once again got an opportunity to vote.

President Aristide represents the other side of Haitian politics. A Catholic priest expelled from his order for his vehement and radical populism, he speaks for the country's impoverished majority. The immediate question for Haiti now is whether he can distinguish between the old Duvalierists and legitimate businessmen with an interest in the investment and trade that is essential to revive a stunted economy.

If not, Haiti will sink again into its own kind of class warfare and despair. President Aristide's order that the previous government not be permitted to leave the country is not a promising beginning, because most of those people are reformers in good faith. Extreme poverty makes it difficult to sustain the patience and tolerance that democracy requires, and Haiti is not only the poorest country in the Western Hemisphere but one of the few in which the standard of living is lower now than a generation ago. Two-thirds of its people are illiterate. Their experience with self-government is nil.

But if the coming months are a great test for Haiti and for President Aristide, they are equally a test for Haiti's neighbors -- most notably the United States -- who set free elections as the condition of the aid that the country desperately needs. The elections have been held, and the winner is now in office. What is the UnitedStates prepared to do to help him and his country? The inauguration imposes heavy responsibilities on the new president. But it also imposes responsibilities on those countries that consider themselves the agents and defenders of democracy.