If the Rouse Co. is tops in the business of building stylized urban malls like Baltimore's Harborplace and the new South Street Seaport, who's the leading candidate to be No. 2?

Rouse.

James W. Rouse, that is. The 68-year-old founder and chairman of Rouse Co., who retired from active management three years ago, has embarked on a new venture building projects similar to those identified with the company that bears his name.

Last month, Rouse's firm, Enterprise Development Company, opened its first major project to rave reviews: Waterside, in Norfolk, an 80,000-square-foot collection of shops and restaurants that is evocative of Harborplace in design and execution.

Although the projects of Rouse's new company seem similar to those of his original firm, the philosophy behind them is different, reflecting the concern for social issues that Rouse espoused in creating its headquarters community of Columbia, two decades ago.

Enterprise Development is the money-raising arm of the Enterprise Foundation, a Rouse-founded organization devoted to providing money and expertise to improve housing conditions for the poor.

"I've always had the notion that somehow if you created a business whose profits flowed into a charitable foundation, that would be a good thing to do," Rouse says.

Profits aren't flowing from one to the other yet, says Edward L. Quinn, the foundation's president, but the foundation is expected to begin reaping the fruits of projects like Norfolk in 1987, and forecasts income of $6 million to $8 million a year from Enterprise Development after 1990.

In the meantime, Rouse has raised more than $12 million for the 2-year-old foundation from individuals and corporations, including $1 million from the Atlantic Richfield Foundation, the oil company's charitable side. The money is being used for housing projects in 11 cities, including Washington and Baltimore.

Besides the Norfolk project, Enterprise Development has also opened Brown's Arcade, a small retail area on North Charles Street in Baltimore, and construction of a retail and hotel complex in Toledo, called Portside, is underway.

Confusion with the Rouse Co. is inevitable, and so is the question of competition. But officials of both companies say there's no conflict between the two. Rouse president Mathias J. DeVito sits on the Enterprise Foundation board.

DeVito says Enterprise Development complements Rouse Co. by handling projects smaller than Rouse is able to do. He believes Norfolk will prove whether small Harborplace-type projects are practical.

Of the possibility the two companies might find themselves competing in a limited market for urban redevelopment, Rouse says: "There's enormous work to be done out there, so there's plenty of room for us both to operate."

Rouse believes there is even more work for the charitable side of his new enterprise. "It's my belief that the greatest neglected need of this country is the need of the poor. You don't see a lot of fundraising efforts for the poor."

Rouse says he believes that through improved housing, the poor can be encouraged to advance in other areas. But poor people usually have trouble finding financing and building-rehabilitation help. That's where the Enterprise Foundation comes in.

The foundation seeks out neighborhood groups, using their ideas and management for housing projects for the poor, and provides as much assistance as possible to accomplish the goals.

The foundation's activities have their roots in Jubilee Housing, a program started by a church group in the Adams Morgan section of the District several years ago and backed by Rouse.

Jubilee purchases older buildings and renovates them for tenant-managed housing for the poor. The project has grown to six buildings with 214 units, and there are plans to expand in a few years to 400 units, about 20 percent of the housing in Adams Morgan. Jubilee has also branched into other commercial ventures and community-service projects, such as a job-placement service.

A typical Enterprise Foundation project is based on a proposal made by a small grass roots group--often church-related--for developing urban housing for the poor. The foundation looks for groups with innovative ideas about rehabilitating buildings for the poor, such as the use of more efficient materials or unique financing schemes. The foundation usually contributes $300,000 or $400,000, Quinn says. It hopes to make $2 million in grants of its own this year and administer $1.5 million from the Ford Foundation.

Rouse says he hopes the Enterprise Foundation will expand its housing projects to 100 cities and serve as a model for other private efforts and for government.

"As we get to the point where we can hold up better lessons, better examples, better experiences . . . then it's my hope that we will stimulate others."