SPRAWL AND TRAFFIC are the terrible twins of this area's explosive growth. Experience suggests that attempts to halt growth are doomed; a wiser goal is to manage it intelligently. Two proposals under debate -- one in Fairfax County, the other in Prince George's County -- do just that, but under vastly different circumstances. The one in Fairfax, backed by developers, calls for a major housing and office project near the Vienna Metro station. The one in Prince George's, opposed by developers, would impose tight caps on the number of home building permits issued next year in the still largely rural area along the county's southern and eastern rims.

Fairlee-MetroWest would be one of the biggest recent residential developments in Fairfax. It includes 2,000 apartments and townhouses, two 12-story office towers, a supermarket, and other businesses or stores. Coupled with nearby projects that are in the works or may soon be, some 4,000 residential units could be built around the Vienna Metro station. Some neighbors are understandably concerned about the impact on roads and schools, but there are obvious advantages to development taking place within walking distance of Metro stations, and the county master plan supports the idea. It makes particular sense in Fairfax, which generated 129,000 new jobs in the 1990s but not nearly enough dwellings to house those employees. As for traffic, the developers of the project would build a four-lane road across Interstate 66, connecting Lee Highway to the Metro station.

The Prince George's proposal seeks to slow growth, at least temporarily, in an area where that seems advisable: a 150-square-mile swath, roughly in the shape of a "J," that comprises a third of Prince George's landmass but just 1 percent of its population. The rolling farmland in the east along the Patuxent River and in the south bordering Charles County was once tobacco country; today, it is sprouting large houses. The county's General Plan, adopted in 2002, sets a slow-growth target for the "rural tier": about 1 percent of the county's total home building permits per year, or about 25 permits annually at current rates. That target has been exceeded -- last year Prince George's handed out about 70 permits -- and the proposal before the council would slash it back to 25.

County officials say the measure would take effect for a year while they worked out legislation to preserve the rural tier. Developers argue that if Prince George's doesn't allow big new houses on large lots, the county's well-heeled strivers will simply move elsewhere. But preserving one of the Washington area's vanishing bucolic enclaves would itself enhance the quality of life in the county. In choosing which land to develop and which to preserve, both counties are moving in the right direction.