GROWTH, ITS EFFECTS and its management constitute the overwhelming challenge to local governments in burgeoning Northern Virginia. The region now has a hard-won national reputation for combining high-tech commerce and a favorable quality of life. But on the ground the balance seems fragile and in need of ever more tough-minded tending, and nowhere more so than in the region's dominant jurisdiction, Fairfax County.

FAIRFAX COUNTY

Kate Hanley (D) is running countywide to be returned as chairman of a Democratic-majority board of supervisors. She knows the details and sees the connections and would be an excellent choice even if she had serious opposition, which she does not.

In other contested races:

In Mason District, incumbent Penny Gross (D) is opposed by former supervisor Tina Trapnell (R). Both have labored to civilize, without choking, Fairfax's dizzy growth. Ms. Trapnell has had trouble dispelling suggestions of offering a thin welcome to the county's fast-growing immigrant population. Ms. Gross is author of a "Kaleidoscope" program promoting respect for diversity. We support her.

In Dranesville District, incumbent Stu Mendelsohn (R) speaks for the high-tech new Fairfax. He got something of a bum rap on the contentious Evans Farm rezoning. His opponent, Barbara Phillips (D), plays off his fast-lane style, emphasizing citizen advocacy and "smart growth." But she does not match his capacity to see the evolving big picture. We would leave Mr. Mendelsohn in place.

In Hunter Mill District, Robert Dix Jr. (R), another incumbent, has waded into fights without minding his opponents' sensibilities. He is convinced -- not everyone is -- that growth pays the bills for quality of life. Challenger Cathy Hudgins (D) brings county-staff savvy and a feel for neighborhoods to her first run for office. John Thoburn's (independent) personal obsession with doing in Bob Dix disqualifies him. We favor Ms. Hudgins.

In the contest for Fairfax sheriff, his former deputy, Stan Barry (D), whom he fired for it, is taking on incumbent Carl Peed (R). The firing turned a necessary debate over law enforcement into a slurring match conducted mostly by Sheriff Peed. It was left to the professional law enforcement groups, with their endorsements of Mr. Barry, to make the weightiest contribution to this campaign. We support Mr. Barry.

ARLINGTON COUNTY

In Arlington, voters will choose among four candidates for the two county board seats held by chairman Paul Ferguson (D) and Mike Lane (R). The two are running for reelection against challengers Charles Monroe (D) and Frances Finta (R). Mr. Ferguson, seasoned and able, should be reelected. The real race is between Mr. Lane and Mr. Monroe. Mr. Lane beat his opponent narrowly in a special election just five months ago, becoming the first Republican to hold Arlington public office since 1983. He has met his promise of fresh perspectives, even while drawing criticism from Mr. Monroe for supposedly leaning toward developers. Mr. Monroe has run a strong campaign, emphasizing the need to make Arlington a "livable, caring, learning community," but Mr. Lane is a leavening addition and deserves reelection.