On Main Street in historic Ellicott City, people browse antique stores and linger over coffee and newspapers. A flight of stairs up from many of the shops, storekeepers can live above their businesses, and investors find renters willing to pay as much as $1,000 a month for an apartment. At both ends of Main Street, retail stores give way to small office buildings.

That kind of mix, where commercial and residential meet on the same block, has worked in Ellicott City for more than 100 years.

Today, updated versions of that mix are all the rage in planning circles nationwide, regarded as solutions for sprawl and a way to satisfy a craving for the days when communities were designed around people, not cars.

Howard County officials thought so much of the idea that in 1990, they marked a half-dozen parcels of land for mixed-use development.

A decade later, none of those sites contains such a project, and the concept's failure to catch fire has come to illustrate how difficult it is for governments to use land-use rules to contain sprawl.

Only one set of mixed-use plans, for a smallish piece of land in southeastern Howard, is moving forward without major controversy. Other sites are for being turned into office developments and, in one case, a quarry. Where mixed-use projects have been proposed, formidable public opposition has so far kept them from being built.

The projects are more complex and often much more difficult for developers, who must deal not only with complicated zoning requirements but also with different markets for housing, retail and commercial development. And, because of their relatively large size and high density, mixed-use projects often become targets for opposition.

"It is a problem," said Joseph W. Rutter, Howard's planning and zoning director. "There is this perception that part of the American dream is to not be able to see your neighbor, much less touch them."

One section of Howard County that has had success with mixed-use development is Columbia. Planners put small shopping areas and community centers within walking distance of neighborhoods, giving residents easy access to places to buy groceries, get shoes repaired and have clothes cleaned.

Ernest Ballard, 54, lives in the Shadow Oak Condominiums in Columbia's Oakland Mills village. An easy walk away are three schools, an ice rink, a community center and a shopping area with a grocery store, dry cleaner, saloon and barbershop. Nearby is an office park that blends in well with surrounding town houses and single-family homes.

This is the picture of mixed use, although modern versions carry labels such as "neotraditional" and feature larger employment centers and more densely clustered housing.

Ballard likes the convenience of the stores, and his grandson, who attends Stevens Forest Elementary School, sometimes walks to Ballard's home from school. But Ballard drives out of Oakland Mills to play basketball, see a doctor and go to work at a nearby medical supply warehouse. Although he doesn't want a long commute, he said, he likes the sense of "getting out of your neighborhood for a day."

Still, Ballard said the convenience was something he was looking for when he moved in five years ago.

Proponents of mixed-use developments say that's the idea. Give people the option of walking to work so their cars might not join the others crowding the highways. Give them a community focal point where they can socialize. It's not Utopia, but it would help, Rutter said: "We realize not everyone is going to ride their bike down to the corner store to get groceries."

In designating the mixed-use sites and following up with mixed-use zoning rules in 1993, Howard planners said such projects had to include at least 20 percent residential units and 15 percent employment and reserve at least 35 percent as open space. Marsha McLaughlin, deputy planning and zoning director, said they wanted to give developers some flexibility and encourage them to try more progressive projects, including the neotraditional kind, like Kentlands in Montgomery County. "I think we were hopeful that one or more might try the neotraditional approach," she said.

One is trying it today, but he is being fought by scores of area residents. Stewart J. Greenebaum, president of Greenebaum and Rose Associates Inc., would like to transform about 500 acres in Fulton into a neotraditional project, with more than 1,100 homes and more than 1 million square feet of retail and commercial space. The prospect of that project and another huge one planned nearby by the Rouse Co. has many neighbors worried about the impact on the area and skeptical that developers can deliver the kind of communities they promise.

"The concept is supposed to draw everything to a center focus, and I really don't see where they've provided that draw, that attraction to bring a new community together," said Greg Fries, president of the Southern Howard Land Use Committee. Greenebaum also has testified in zoning board hearings that the development probably could lure a Fortune 500 company, but Fries is doubtful.

Indeed, some mixed-use developments lack a large employment component, said Marya Morris, a senior research associate with the American Planning Association. And when they are included, it's sometimes difficult to change attitudes about commuting so that people might consider working closer to home.

"People no longer think that a 45- to 50-minute commute is a big deal," Morris said. As a result, she said, mixed-use developments often don't show much difference from typical subdivisions when it comes to traffic impact. But when they're good projects, they're really good, she said: "In terms of creating a sense of community and a desirable place to live, they absolutely have been a slam dunk."

In Howard, one site north of Interstate 70 near Marriottsville Road wasn't zoned mixed use but is turning out that way, pieced together by developers who were ready before the zoning classification was created.

That and the 42-acre Cherrytree project in southern Howard County are the only two new mixed-use developments proceeding unimpeded. The Rouse Co. proposal is being fought in court, and the Greenebaum case, delayed several times, is dragging on before the zoning board.

Another mixed-use site was split by Route 100, half of it sold for office development, the other piece still awaiting development plans. A small parcel at Route 40 and Rogers Avenue is likely to develop as office space instead of mixed-use because a strong market for offices could mean higher profits than a mix of development would generate. The last of the mixed-use group, a site east of Interstate 95, will see a mixed-use project only if current plans to build a quarry fall through.

Uri P. Avin, the former Howard planning and zoning director who wrote the 1990 General Plan that created the mixed-use designation, said he's not discouraged. "Part of it is the market. The market in the early '90s was not strong," he said. "And these kind of projects take time."

But Avin said county officials should persevere with the goals of a decade ago. "This is a desirable kind of development, and the county ought to be encouraging it," he said.