THE APPOINTMENT of people to senior government posts is partly about competence and qualifications. Everyone wants to think that the individual in charge of the Coast Guard or U.S. policy in the Horn of Africa has some basic familiarity with river patrols and the politics of Somalia, respectively, and some basic ability to manage. But appointments are also about perceptions and symbolism: They tell the public what the administration thinks about the department or agency in question, and give broader clues about the administration's philosophy. For that reason, it is worth flagging a potential concern about Michael Garcia, the former federal prosecutor who has just been appointed acting commissioner of the Immigration and Naturalization Service.

This is not to question Mr. Garcia's competence and qualifications: He is a former federal prosecutor who handled the 1993 World Trade Center bombing, as well as the prosecution of al Qaeda operatives who bombed American embassies in East Africa. More recently, he has worked on export enforcement in the Commerce Department. He has been appointed only temporarily, to shepherd the INS into its new home in the Homeland Security Department, although he may well later emerge as one of that department's leading lights. He was praised by Attorney General John D. Ashcroft as someone who will "lead tough enforcement of our immigration laws to protect Americans."

The trouble is that symbolically, Mr. Garcia represents only one half of the mission of the INS. Along with policing borders, the INS is also responsible for issuing work permits and green cards, and for naturalizing the immigrants who are already here. Many fear that in the wake of the agency's move to Homeland Security, that half of its mission will be lost in the rush to keep people out; Attorney General Ashcroft's words about Mr. Garcia's "tough enforcement" background will not cheer them. Their fears need not be realized: There are many possibilities for expanding the role of the new Bureau of Citizenship within the Homeland Security Department -- the half of the INS devoted to "service" as opposed to enforcement -- as well as for making it more efficient. But much depends on who is appointed to do that job, and what philosophy and background he or she brings to it. Mr. Garcia's appointment buys the administration some time to think about the evolution of American policy toward those immigrants who are welcome here, as well as those we want to keep out. Let's hope it is well used.