The large banner hanging from the airport control tower reads, "Welcome to Burkina Faso: burial ground of imperialism."

Such rhetorical flourishes are common in this impoverished, landlocked West African state formerly known as Upper Volta, since Capt. Thomas Sankara took power in August 1983.

Burkina Faso -- meaning land of upright people -- is one of the poorest countries on a continent that dominates lists of the world's poorest developing countries.

The few paved streets of the capital, Ouagadougou, are mostly plied by bicycles and mopeds, for automobiles remain a major luxury in this country. The average citizen's daily preoccupation is often where to find enough firewood to prepare food.

Instead of the customary Mercedes-Benz limousine used by dignitaries throughout the region, Burkina officials use modest Renaults.

Despite Burkina Faso's poverty, President Sankara has succeeded in instilling a sense of optimism here. Under his leadership, the government has been entirely revamped. Administrative structures inherited from French colonialism have been replaced by "popular" organs known as committees for the defense of the revolution.

According to Capt. Blaise Compaore, the country's number two man and the leader of the coup that brought Sankara to power, the chief role of the committees is to "conscientize" the masses.

A senior western diplomat in Ouagadougou said that "the major success of this government, and the [committees], has been in getting people involved."

Prior to Sankara, the vast majority of the population mostly composed of peasants, "didn't even know where Ouagadougou was," the diplomat said.

IN THE TOWNS, street children who sell cigarettes singly from open packets on street corners and handicapped polio victims have been organized by the defense committees and given places to sleep. Some have been taught crafts and encouraged to sell their works to tourists, rather than beg.

In the countryside, where roads are few, and their use limited by the seasons, the committees have taken over the administrative role formerly assumed by traditional chiefs, and they maintain contact between outlying regions and the central government.

EARLY THIS year, in an impressive display of what is known as "popular mobilization," the committees organized a nationwide program to vaccinate children. It was dubbed "Operation Commando."

When the program was announced, western aid donors tried to dissuade the government from attempting to vaccinate all of the country's children simultaneously against three common diseases.

Some called the plan foolishly ambitious.

Less than three weeks after its start, Operation Commando had overshot its goal.

Not only had all of the targeted children been vaccinated, but parents in neighboring countries slipped across porous borders with their children, so that they, too, could receive the shots.

After having been highly critical of the idea, the U.N. Children's Fund called Operation Commando one of its "major successes for the year in Africa."

SANKARA'S accession to power has concerned France and Burkina Faso's conservative neighbor to the south, Ivory Coast. Since independence of Burkina Faso in 1960, those two countries have exercised strong influence on both the economy and politics here.

Frequent contacts with Libya and Sankara's firebrand, leftist rhetoric encouraged fears that he was under the sway of Col. Muammar Qaddafi, the unpredictable Libyan leader.

Western diplomats now dismiss that notion, saying that the Ouagadougou government became disenchanted with Libya when promised large-scale aid failed to materialize. Algeria has displaced Libya as the principal of nonwestern aid donor.

When Libya delivered a planeload of used television equipment to mark the second anniversary of the Sankara revolution, the "gift" was returned unceremoniously. A low-level official received a second shipment of new equipment about two weeks later.

During his two-day stopover in Burkina Faso last week, Qaddafi told a mass rally that Libya was "prepared to provide Burkina Faso with anything it needs."

One senior Burkina official said afterward, "We never plan on the basis of these promises, and would be happy to receive the cement and other aid he Qaddafi has promised in the past."

Sankara has sought to make clear that his defiant stances on issues will not be affected by his country's heavy reliance on foreign aid.

Although the United States was the largest food donor to Burkina Faso in 1985, delivering more than 53,000 tons of grain, Sankara has not hesitated to criticize U.S. policies in southern Africa as well as in Central America.