One week after firing the director of the city's HIV/AIDS Administration, District officials announced yesterday that they have hired the leader of a national AIDS advocacy group to improve the understaffed and mismanaged agency.

Marsha Martin has served since 2002 as executive director of AIDS Action, a Washington-based organization dedicated to improving AIDS programs. She will start work as director of the city agency Sept. 7.

"Ms. Martin brings with her a wealth of knowledge and considerable expertise in the field of HIV-AIDS," Mayor Anthony A. Williams (D) said after introducing Martin at his weekly news conference. "She has the skills that are needed to move the agency forward."

Martin replaces Lydia L. Watts, who was fired barely a year after the mayor appointed her to the $114,000-a-year position. The D.C. Appleseed Center for Law and Justice issued a report this month concluding that the city had mismanaged its response to HIV and AIDS in the District, in which an estimated one in 20 residents is infected with the virus.

In firing Watts, D.C. Health Director Gregg A. Pane said he "felt that new leadership was needed" to bring urgency to the city's response to the AIDS epidemic. Pane said yesterday that Martin's professional and academic background was key in her selection, making her "a great leader."

Martin, a District resident, has had a long career in social services. Before becoming director of AIDS Action, she served for three years as special assistant on HIV-AIDS policy to Donna E. Shalala, former U.S. Health and Human Services secretary. She was also the coordinator for homeless veterans' initiatives at the Department of Veterans Affairs and worked under former New York mayor David Dinkins as director of the Mayor's Office on Homelessness and Single Room Occupancy Housing.

Martin said she hoped to make the city's "response to HIV a model for the nation."

Marsha Martin has served since 2002 as executive director of AIDS Action, a national group.