While some local businesses are profiting as a result of the economic slowdown, a healthy number of other firms here are making money the old-fashioned way: doing well at what they do.

Some of the still-growing companies are selling harder or outthinking their competitors. Others are in hot industries, such as the environment or health care. Still others provide fundamentals that customers can't do without -- even if their products seem a bit esoteric to the nonexpert.

Profits at Rockville-based Sage Software Inc., for instance, rose 34 percent in the most recent quarter compared with the same period a year earlier. Sage was one of five local firms named to Forbes magazine's list of the 200 best small companies in America.

Sage has positioned itself at the forefront of its market by being one of the first firms to supply its software-development products to personal computers rather than to large mainframe computers. Sage now sells to about 500,000 software developers nationwide, according to Lin Pearce, executive vice president.

The other four local companies on the Forbes list were American Management Systems Inc. of Arlington, Crown Books Corp. of Landover, Group 1 Software Inc. of Greenbelt and Legent Corp. of Vienna.

Other firms receive less notice because their financial results are not made public, but they are succeeding nonetheless. The Washington area, for instance, is a hotbed of entrepreneurship in the environmental field. One expert estimates it has more environment-related businesses per capita than any other area of the country.

Among the small firms growing in this field are International Science & Technology Inc. of Rockville, which restores polluted lakes; Eco-Concerns Inc. of Takoma Park, a husband-and-wife firm that sells recycled items; and Eagle Management Systems of Washington, a recycling firm.

The environmental movement also has given a lift to Gilberg & Kurent, a Washington law firm that includes environmental law among its specialities. Begun just over a year ago, the firm has grown from nine lawyers to 18 and expects to have 25 by the end of the year.

District-based Congressional Quarterly has seen a surge of new revenue this year because the weekly publication just began accepting advertising. Ad pages, limited to 12 per issue, are expected to bring in nearly $2 million this year -- a net gain over and above CQ's regular subscription revenue.

The federal budget crisis helped boost the ads, which are principally advocacy messages, said CQ editor and publisher Neil Skene. "When everyone was talking about cutting defense, defense contractors wanted to say why their tank or their airplane was good for the country," he said. "You try harder when you are in jeopardy."