By Robert I. Rotberg for Christian Science Monitor

CAMBRIDGE, MASS. - The failed and failing states of sub-Saharan Africa - including Sierra Leone, Liberia, and Zimbabwe - attract the most attention. But a quiet renaissance of positive leadership is taking hold in the region, including the Islamic northeast.

The dominant personalities in such battered places as Somalia and Somaliland are firmly on the side of the United States, and ready to be helped in rebuilding their states. No state in Africa now seeks to harbor terrorists; better rewards are to be found in alliance with the developed world.

In Botswana, Ghana, Senegal, South Africa, and Tanzania, basic human rights are being respected, and there's a promise of better times. After a year of principled leadership, Ghana is in the vanguard of change. If Ghana's gains can be sustained, West Africa will have another model to help transform a neighborhood characterized by fractiousness and meltdown.

Nigeria is a problem case. As Africa's most populous and historically most poorly governed place, its turn to democracy in 1999 seemed dramatic. But President Olusegun Obasanjo has been unable to lead the nation in a wholly positive direction. Too many of Nigeria's Muslim-dominated states have thumbed their noses at the central government. So democratic rule is a phenomenon of the center only, not of the states.

When the ingredients of visionary leadership are lacking, the stew of governance tastes sour. When they are richly available, everyone prospers and AIDS and other scourges seem survivable. The US and UN need to craft new policies to support and encourage responsible leadership skills among elected officials across sub-Saharan Africa.

In South Africa, Nelson Mandela demonstrated leadership without bullying. As president, he was an inclusionist who convinced black South Africans from all backgrounds, as well as coloreds, Indians, and whites, that he was everyone's champion and that he sought a peace dividend for them, not for himself.

Neighboring Botswana, thinly populated and mostly desert, has been an oasis of steady, open rule for more than 35 years. Even before it became the world's greatest producer of gem diamonds, Botswana was well-run. It endured insults and occasional blows from apartheid South Africa, ignored the collectivist and authoritarian fancies of nearby Zambia and Tanzania, and concentrated its energies not on personal enrichment but on encouraging middle-class empowerment amid old-fashioned liberal values.

Festus Mogae, Botswana's president, had excellent role models. His predecessors were participatory, sensible, and focused on what was good for their peoples, not for themselves and their families. Sir Seretse Khama, Botswana's first president, had the charisma and stature to have gone either way. His presidencies (from 1966 to 1980) coincided with the heyday of African single-party rule, state interventionism, Afro-socialism, and nonalignment masquerading for self-aggrandizement. He could have followed the examples of Kwame Nkrumah of Ghana, Julius Nyerere of Tanzania, and Kenneth Kaunda of Zambia - all well-intentioned leaders who confused personal preference with platonic wisdom.

Botswana's President Khama set a different tone for sub-Saharan Africa. He shunned motorcades, promoted by merit, insisted on orthodox methods of governance, and, most of all, measured his accomplishments by improvements in living standards, educational and medical facilities, and the quality of deliberative democracy. Many argue that Mr. Mandela and Khama inherited structures conducive to good government. If so, then neighboring Zimbabwe should have remained participatory and prosperous. Instead, it fell into the clutches of a ruthless autocrat. Under Robert Mugabe, Zimbabwe is now the poster child of chaos and man-made shortages.

President Mugabe fits in the same malign mold as Mobutu Sese Seko of Zaire/Congo, Idi Amin of Uganda, and Jean-Bedel Bokassa of the Central African Republic. For them, people's needs were irrelevant. It's true that sub-Saharan Africa has arbitrarily arranged postcolonial states, many too small, resource-poor, landlocked, and infused with diseases to prosper easily. Disease weakens resilience in the face of oil shocks, raw-material price collapses, and the venalities of the ruling classes.

For many of those reasons, in the very decades when Asians prospered, black Africans experienced declining standards of living and massive reductions in life expectancies. For many millions, freedom never produced peace dividends. In Asia, positive leadership, not structure or history, made a key difference. In Africa, the difference between participatory and autocratic leaders - between servants of the people and those who believe themselves anointed and all-knowing - is the key to success and failure.

Levels of schooling, world views, and prior experience do not seem to matter. Mugabe is among the most educated and worldly of Africa's leaders. Sub-Saharan Africa will continue to lurch from crisis to crisis so long as positive leadership is not strongly supported. Washington, London, Brussels, and the World Bank and International Monetary Fund need to provide tangible incentives for good leadership.

• Robert I. Rotberg directs Harvard's Program on Intrastate Conflict and is president of the World Peace Foundation.