The front-page picture of Nov. 26 is one to keep. It shows Tom Ridge, a wide grin splitting his prizefighter's face, accepting congratulations from a circle of well-wishers on being named the first secretary of the Department of Homeland Security, moments after President Bush signed the legislation creating the Cabinet department.

Today that department is little more than a gleam in the eyes of Bush, Ridge and the main sponsors of the bill, Democratic Sen. Joe Lieberman of Connecticut and Republican Rep. Dick Armey of Texas. The department has no headquarters, only three appointed officials -- Ridge and two deputies -- and 170,000 prospective employees scattered among 22 agencies who are wary of what the merger will mean for them.

In the weeks and months ahead, there will be many occasions to look at that picture and wonder, "What the heck was he smiling about?" Among those almost certain to ask that question is Ridge himself. According to friends, he was anything but eager for the appointment and would have preferred to stay as the White House director of homeland security, coordinating the work of the department with old-line agencies, rather than presiding over this vast new bureaucracy himself.

Aides insist that the only issue was whether Ridge would make his stay in Washington longer and move his family here from Pennsylvania. In any case, Ridge answered the president's summons, just as he did more than a year ago when he gave up his job as governor of Pennsylvania to join the White House staff.

In the past year, Ridge has gained the trust and earned the respect of members of Congress and state and local officials with whom he has worked. But the task ahead is huge. Paul Light, the Brookings Institution and New York University expert on government organization and personnel, says it's "the most difficult bureaucratic reorganization since the Roman Empire tried to take over the administration of Egypt."

That one ended badly for both Caesar and Cleopatra. The more pertinent and contemporary example is the creation in 1977 of the Department of Energy out of a mix of separate regulatory and operating agencies. "That one has never jelled," Light said. "The windmill types are still fighting with the nuclear power folks, and the conservation people still argue with everybody."

Ridge confronted one challenge immediately by meeting with the heads of federal employee unions in an effort to smooth over the dispute on union representation rights that had delayed Senate passage of the legislation. But great tension remains about changes of assignments and shifts of responsibility for both senior managers and front-line workers.

Last June, when Bush abandoned his earlier objections and embraced the concept of a new department, which had been pushed by Lieberman and other Democrats joined by a few congressional Republicans, the National Journal reported that critics thought "a sprawling, showy, distracting Department of Homeland Security . . . is both too much and too little."

Too much because it pulled in agencies such as the Coast Guard with many functions unrelated to protecting against terrorists. Too little because the FBI and the CIA remain separate and independent agencies, under obligation to supply intelligence to the new department but not subject to the command of Ridge.

Light sees other challenges ahead. "It would be difficult to coordinate 22 separate agencies under the best of circumstances," he said, "but there is great unevenness among these 22. Several are damaged goods. The INS [Immigration and Naturalization Service] has been under fire, and now it will be sawed in half -- the second major reorganization in nine months. Customs is in the midst of a major overhaul. FEMA [the Federal Emergency Management Agency] seems to be going through a difficult transition. The Coast Guard is very well run but has an aging fleet. And there is a huge variation in the quality of the technology in the different agencies. The basic organizational systems will have to be reconciled."

White House and Office of Management and Budget officials have been working on plans for bringing the department into being. The timetable calls for the new structure to be in place by March 1, but almost everyone is cautioning that it will take much longer for it to function with any degree of effectiveness.

The Department of Defense offers a cautionary tale. More than 40 years after Harry Truman called it into being, Congress found it had to pass major legislation to correct structural problems that made it difficult to resolve disputes among the military services. The Department of Homeland Security, too, will have Tom Ridge grimacing, rather than grinning, before it finally is whipped into shape.