Washington

Rita Colwell will step down on 21 February as director of the National Science Foundation (NSF), the agency that supports most non-biomedical research in the United States, after five-and-a-half years in charge.

Colwell, the first woman and only the second biologist to lead the NSF, announced her departure at the 11 February hearing of the House Committee on Science. “It's been a wonderful run,” she said afterwards. Arden Bement, a metallurgist who heads the National Institute of Standards and Technology, will run the agency until the White House chooses a permanent successor.

Colwell will now head up Canon Life Sciences, a new offshoot of the electronics company. She is resuming her professorship at the University of Maryland, College Park, and taking one up at Johns Hopkins University in Baltimore, where she will help develop a centre for the study of infectious diseases.

During her tenure, the NSF's budget grew by two-thirds, from US$3.4 billion in 1998 to $5.6 billion this year. The average annual NSF grant rose from $90,000 to $142,000, she points out, and graduate student stipends almost doubled, to $30,000. “She's certainly been effective,” says one Senate staffer.

More controversial were the millions of dollars spent on large projects, including $300 million for a gravity-wave detector and $219 million for a network of geological observatories.

The management of these projects was criticized in the Congress (see Nature 418, 573; 200210.1038/418573a) and Colwell's insistence that all of them were progressing satisfactorily irritated some. “She drove them nuts from time to time,” says Joel Widder, a lobbyist and former senior NSF official who has worked for a congressional committee overseeing the agency. “She would continually insist that everything was on time and on budget.”

And Colwell, a marine biologist, had mixed results in raising money for her first love, environmental and ecological research. In 2000, she launched an interdisciplinary initiative on biocomplexity, which to date has received $334 million. But she was unable to implement a much larger move by the agency into environmental science proposed in 1998 (see Nature 395, 4; 199810.1038/25562).

Some were surprised at an outsider being appointed as the agency's interim leader. But Bement is seen as a safe pair of hands — he knows the NSF well, having served on its governing board for six years from 1989.