The welcome recent announcement that the United States is willing to join face-to-face talks with Iran rekindled memories of my own experiences, 25 years ago, as chief negotiator in the Iranian hostage crisis. The subject of that negotiation was the 52 American diplomats who were taken hostage in Tehran on Nov. 4, 1979. The result was their release, 444 days later, on Ronald Reagan's 1981 inauguration day. Since that day we have had no diplomatic relations with Iran.

There are obvious differences between the situation in 1979-81 and now. Then it was the United States that wanted face-to-face negotiations. Today it is Iran that wants direct talks — talks that will help make up for what its leaders view as decades of humiliation and abuse by America. While the negotiations 25 years ago involved the future and well-being of 52 individuals, the 2006 negotiations would deal with a problem that potentially threatens millions.

Nevertheless, there are lessons from our 1979-81 negotiations with Iran that can inform our efforts in 2006. First, we must be sure we are talking with the right people. One of the most frustrating dead ends we encountered in the hostage negotiations was learning that despite prolonged efforts to forge a settlement with President Abolhassan Bani-Sadr, he did not even have the power to move the hostages from one location to another, much less cause their release. If our 2006 negotiators study the vectors of power in Iran, they may be able to avoid such frustrations.

At the moment, Iran's president, Mahmoud Ahmadinejad, is riding high. But he may not be as powerful as he seems and power may shift over time. Ultimate authority remains with Ayatollah Ali Khamenei, and we have not heard from Ali Akbar Hashemi Rafsanjani, former two-term president and now chairman of the Expediency Council. In short, we should look for seams, even small ones, in the cloak of power.

Second, our negotiators should prepare themselves for what might be called "bazaar behavior." For all my difficult dealings with interlocutors like China's foreign minister, Qian Qichen, I always knew what he really wanted and that if an agreement was reached, its terms would be carried out. But with the Iranians, the negotiating style is likely to resemble that of a Middle Eastern marketplace, with outlandish demands, feints at abandoning the process and haggling over minor details.

Even after the agreement was signed on Jan. 19, 1981, the Iranians disavowed a vital technical annex. To bring them back in line, I directed the pilot of my plane, on a telephone line that I knew was tapped, to warm up the engines. The Iranians quickly dropped their claim, and a day later the hostages were released.

If the Iranians ultimately come to the table, our negotiators will need to be patient, almost superhumanly so. The subtext for everything the Iranians do and say will be their historic sense of grievance against the U.S., stretching back at least to the C.I.A.-engineered overthrow of the government and restoration of the shah to his throne in 1953.

The hostage crisis probably dragged on because the Iranians wanted to maximize their exposure on the world stage and to humiliate the Great Satan (and its president) for as long as possible. One bewildering delay occurred when the Iranians refused to sign any direct agreement with the United States. We finally suggested that the agreement take the form of mutually dependent promises to Algeria, and that was acceptable for reasons that still remain obscure.

Third, if the new package of incentives offered by Britain, China, France, Germany, Russia and the United States does not persuade the Iranians to suspend their enrichment program, which was Washington's condition for joining the talks, I believe sanctions can play a valuable role. The hostage crisis shows that we must assemble the broadest possible spectrum of participants, including the Russians, in any sanctions regime. Although enforcement we achieved through the United Nations began to fray toward the end of the 444-day ordeal, they plainly had an impact on the Iranian population.

As in the hostage crisis, a military solution is unwise and probably infeasible. Though possible use of our military should not be taken off the table, we must stay on the diplomatic and, if necessary, the punitive economic track. Our negotiators must be firm and resolute not just with their counterparts, but with those in the press, the administration and the public who will inevitably pressure them to declare prematurely that the talking is over.

Shortly before Christmas in 1980, in the gloom of a defeated administration, we received a message from the Iranians tripling their monetary demand to $24 billion for the release of our hostages. I was tempted to pull the plug and leave the matter for resolution by the incoming Reagan administration, but I concluded we had come too far to give up. Ultimately, those demands were dropped and the negotiations concluded on terms similar to what we had previously offered. When those who represent America in any coming negotiations face similar moments — and they inevitably will — I hope they will recognize that persevering is indispensable to our national interest.

Warren Christopher, secretary of state from 1993 to 1997, is the co-chairman of the Pacific Council on International Policy. He wrote this commentary for The New York Times.