It was “the poshest crowd of the year,” proclaimed one society columnist. Gathered for the opening night of the Johannesburg Art Fair were the multihued members of South Africa’s prosperous post­apartheid elite—unshaven white hipsters speaking English in boarding-school accents; jowly old Afrikaners, descendants of the Dutch settlers, who ruled the country oppressively into the 1990s; lissome black women, their dresses slight and their hair straightened, sipping Stellenbosch wines alongside their well-tailored dates, members of a young class of black-township-born tycoons.

Colin Ainsworth Sharp, a silver-haired white British émigré who has lived in South Africa for more than 40 years, surveyed the scene. “There are a whole lot of slick-looking black guys here,” he said, an ironic testament both to how much has changed and to differences that linger. A man of conservative leanings, Ainsworth Sharp, who resides on a country estate and publishes a decor magazine named Habitat, belongs to a social class that once expressed open fear that rule by the country’s black majority would lead to chaos. But now he gushes about Nelson Mandela, the imprisoned revolutionary who became the country’s first black president, in 1994. Ainsworth Sharp’s wife redecorated the now-retired president’s house, and he raved to me about the great man’s “aura of charisma.”

Diamond Moshiga, a black bank executive, expressed similar sentiments as he studied an abstract oil-and-crayon work by Ernest Mancoba, a mid-20th-century South African who moved to France to escape apartheid. Moshiga was shopping for something that would appreciate in value and also look good on the walls of his home, in a once white-dominated suburban enclave. “It’s some kind of prestige to be associated with this,” he said, “considering where we came from.”

South Africa has indeed progressed immeasurably since the days when a white government kept people like Moshiga powerless and poor. The system of apartheid, which evolved over many years, assured an abundant pool of cheap black labor to work in white-owned factories, homes, and gold mines, while a brutal police force stymied most black political activity. Then, nearly two decades ago, the combined force of moral condemnation and crippling economic sanctions brought about one of the most remarkable peaceful transfers of power the world has ever seen. Majority rule, which in practice has meant a one-party government led by the once-outlawed African National Congress, brought 14 years of peace, stability, and startling economic growth, driven by global demand for South Africa’s precious metals and other commodities. Yet outside the gala that night, a simmering, ominous mood was stirring in the country.

Part of the problem is universal: The global recession has sharply decreased demand for commodities and has halted investment in developing nations. (The Institute for International Finance estimates that net private capital flows to emerging markets will plunge to $165 billion this year, down from a high of $929 billion in 2007.) But the economic downturn has coincided with—and exacerbated—a political crisis that is unique to South Africa, brought about by the rise of Jacob Zuma, the firebrand political leader who will almost certainly become the country’s next president later this year. Many South Africans say Zuma’s ascension has led to the most profound division their country has faced since the early 1990s. Then, as it had been for centuries, the divide was between black and white. This time, the conflict, perhaps even more vexing, is between rich and poor.

Since he won a contentious internal contest to lead the ANC, in December 2007, Zuma, a self-proclaimed socialist with a history of legal troubles involving a skein of charges from bribery to rape, has taken South African politics on a roiling ride, frightening much of the population and raising questions about the durability of the nation’s spirit of reconciliation. This past fall, Zuma and his loyalists forced the resignation of President Thabo Mbeki, who was Mandela’s handpicked successor, and installed a caretaker to rule the country until an election, which will be held sometime this year. Zuma, who will be the ANC’s candidate, styles himself as a militant African populist: blunt in speech, openly polygamous (he celebrated becoming party leader by marrying a second wife and has since taken a third), and often photographed wearing the traditional leopard-skin finery of a Zulu warrior. In an attempt to capitalize on the lower classes’ resentment of the country’s vast income disparity, he has called for the government to spread South Africa’s wealth to the dispossessed. Toward that end, he has the backing of the ANC’s formidable left wing, a coalition of trade unions, communists, and other critics of the party’s cozy relationship with business in the postapartheid years.

After Zuma clinched victory in the party-leadership race, the Johannesburg Stock Exchange went into a tailspin that was subsequently exacerbated by an electricity crisis and the worldwide economic downturn. To a substantial swath of both the white and black populations—who believe that South Africa stands apart from the chaos, corruption, and political turmoil that plague much of the rest of Africa—the change has come as a shock, one of a series of developments that have provoked worries of, as a column in the South African newspaper Business Day put it, “a creeping ‘Nigerianization.’ ”